diff --git a/vnpy/app/spread_trading/base.py b/vnpy/app/spread_trading/base.py
new file mode 100644
index 00000000..574dc9b9
--- /dev/null
+++ b/vnpy/app/spread_trading/base.py
@@ -0,0 +1,156 @@
+from typing import Dict, List
+from math import floor, ceil
+from datetime import datetime
+
+from vnpy.trader.object import TickData, PositionData
+from vnpy.trader.constant import Direction
+
+
+class LegData:
+    """"""
+
+    def __init__(
+        self,
+        vt_symbol: str,
+        price_multiplier: float,
+        trading_multiplier: float
+    ):
+        """"""
+        self.vt_symbol: str = vt_symbol
+
+        # For calculating spread price
+        self.price_multiplier: float = price_multiplier
+
+        # For calculating spread pos and sending orders
+        self.trading_multiplier: float = trading_multiplier
+
+        # Price and position data
+        self.bid_price: float = 0
+        self.ask_price: float = 0
+        self.bid_volume: float = 0
+        self.ask_volume: float = 0
+
+        self.long_pos: float = 0
+        self.short_pos: float = 0
+        self.net_pos: float = 0
+
+    def update_tick(self, tick: TickData):
+        """"""
+        self.bid_price = tick.bid_price_1
+        self.ask_price = tick.ask_price_1
+        self.bid_volume = tick.bid_volume_1
+        self.ask_volume = tick.ask_volume_1
+
+    def update_position(self, position: PositionData):
+        """"""
+        if position.direction == Direction.NET:
+            self.net_pos = position.volume
+        else:
+            if position.direction == Direction.LONG:
+                self.long_pos = position.volume
+            else:
+                self.short_pos = position.volume
+            self.net_pos = self.long_pos - self.short_pos
+
+
+class SpreadData:
+    """"""
+
+    def __init__(
+        self,
+        name: str,
+        legs: List[LegData],
+        active_symbol: str
+    ):
+        """"""
+        self.name: str = name
+
+        self.legs: Dict[str, LegData] = {}
+        self.active_leg: LegData = None
+        self.passive_legs: List[LegData] = []
+
+        for leg in legs:
+            self.legs[leg.vt_symbol] = leg
+            if leg.vt_symbol == active_symbol:
+                self.active_leg = leg
+            else:
+                self.passive_legs.append(leg)
+
+        # Spread data
+        self.bid_price: float = 0
+        self.ask_price: float = 0
+        self.bid_volume: float = 0
+        self.ask_volume: float = 0
+
+        self.net_pos: float = 0
+        self.datetime: datetime = None
+
+    def calculate_price(self):
+        """"""
+        self.clear_price()
+
+        # Go through all legs to calculate price
+        for n, leg in enumerate(self.legs.values()):
+            # Filter not all leg price data has been received
+            if not leg.bid_volume or not leg.ask_volume:
+                self.clear_price()
+                return
+
+            # Calculate price
+            if leg.price_multiplier > 0:
+                self.bid_price += leg.bid_price * leg.price_multiplier
+                self.ask_price += leg.ask_price * leg.price_multiplier
+            else:
+                self.bid_price += leg.ask_price * leg.price_multiplier
+                self.ask_price += leg.bid_price * leg.price_multiplier
+
+            # Calculate volume
+            if leg.trading_multiplier > 0:
+                adjusted_bid_volume = floor(
+                    leg.bid_volume / leg.trading_multiplier)
+                adjusted_ask_volume = floor(
+                    leg.ask_volume / leg.trading_multiplier)
+            else:
+                adjusted_bid_volume = floor(
+                    leg.ask_volume / abs(leg.trading_multiplier))
+                adjusted_ask_volume = floor(
+                    leg.bid_volume / abs(leg.trading_multiplier))
+
+            # For the first leg, just initialize
+            if not n:
+                self.bid_volume = adjusted_bid_volume
+                self.ask_volume = adjusted_ask_volume
+            # For following legs, use min value of each leg quoting volume
+            else:
+                self.bid_volume = min(self.bid_volume, adjusted_bid_volume)
+                self.ask_volume = min(self.ask_volume, adjusted_ask_volume)
+
+            # Update calculate time
+            self.datetime = datetime.now()
+
+    def calculate_pos(self):
+        """"""
+        self.net_pos = 0
+
+        for n, leg in enumerate(self.legs.values()):
+            adjusted_net_pos = leg.net_pos / leg.trading_multiplier
+
+            if adjusted_net_pos > 0:
+                adjusted_net_pos = floor(adjusted_net_pos)
+            else:
+                adjusted_net_pos = ceil(adjusted_net_pos)
+
+            if not n:
+                self.net_pos = adjusted_net_pos
+            else:
+                if adjusted_net_pos > 0:
+                    self.net_pos = min(self.net_pos, adjusted_net_pos)
+                else:
+                    self.net_pos = max(self.net_pos, adjusted_net_pos)
+
+    def clear_price(self):
+        """"""
+        self.bid_price = 0
+        self.ask_price = 0
+        self.bid_volume = 0
+        self.ask_volume = 0
diff --git a/vnpy/app/spread_trading/engine.py b/vnpy/app/spread_trading/engine.py
index 1e4584b9..5ad45241 100644
--- a/vnpy/app/spread_trading/engine.py
+++ b/vnpy/app/spread_trading/engine.py
@@ -1,6 +1,13 @@
+from typing import List, Dict
+from collections import defaultdict
 
 from vnpy.event import EventEngine, Event
 from vnpy.trader.engine import BaseEngine, MainEngine
+from vnpy.trader.event import EVENT_TICK, EVENT_POSITION
+from vnpy.trader.utility import load_json, save_json
+
+from .base import LegData, SpreadData
+
 
 APP_NAME = "SpreadTrading"
 
@@ -11,3 +18,141 @@ class SpreadEngine(BaseEngine):
     def __init__(self, main_engine: MainEngine, event_engine: EventEngine):
         """Constructor"""
         super().__init__(main_engine, event_engine, APP_NAME)
+
+    def write_log(self, msg: str):
+        """"""
+        pass
+
+
+class SpreadDataEngine:
+    """"""
+    setting_filename = "spread_trading_setting.json"
+
+    def __init__(self, spread_engine: SpreadEngine):
+        """"""
+        self.spread_engine: SpreadEngine = spread_engine
+        self.main_engine: MainEngine = spread_engine.main_engine
+        self.event_engine: EventEngine = spread_engine.event_engine
+
+        self.write_log = spread_engine.write_log
+
+        self.legs: Dict[str, LegData] = {}          # vt_symbol: leg
+        self.spreads: Dict[str, SpreadData] = {}    # name: spread
+        self.symbol_spread_map: Dict[str, List[SpreadData]] = defaultdict(list)
+
+        self.load_setting()
+        self.register_event()
+
+    def load_setting(self):
+        """"""
+        setting = load_json(self.setting_filename)
+
+        for spread_setting in setting:
+            self.add_spread(
+                spread_setting["name"],
+                spread_setting["leg_settings"],
+                spread_setting["active_symbol"],
+                save=False
+            )
+
+    def save_setting(self):
+        """"""
+        setting = []
+
+        for spread in self.spreads.values():
+            leg_settings = []
+            for leg in spread.legs:
+                leg_setting = {
+                    "vt_symbol": leg.vt_symbol,
+                    "price_multiplier": leg.price_multiplier,
+                    "trading_multiplier": leg.trading_multiplier
+                }
+                leg_settings.append(leg_setting)
+
+            spread_setting = {
+                "name": spread.name,
+                "leg_settings": leg_settings,
+                "active_symbol": spread.active_leg.vt_symbol
+            }
+            setting.append(spread_setting)
+
+        save_json(self.setting_filename, setting)
+
+    def register_event(self):
+        """"""
+        self.event_engine.register(EVENT_TICK, self.process_tick_event)
+        self.event_engine.register(EVENT_POSITION, self.process_position_event)
+
+    def process_tick_event(self, event: Event):
+        """"""
+        tick = event.data
+
+        leg = self.legs.get(tick.vt_symbol, None)
+        if not leg:
+            return
+        leg.update_tick(tick)
+
+        for spread in self.symbol_spread_map[tick.vt_symbol]:
+            spread.calculate_price()
+
+    def process_position_event(self, event: Event):
+        """"""
+        position = event.data
+
+        leg = self.legs.get(position.vt_symbol, None)
+        if not leg:
+            return
+        leg.update_position(position)
+
+        for spread in self.symbol_spread_map[position.vt_symbol]:
+            spread.calculate_pos()
+
+    def add_spread(
+        self,
+        name: str,
+        leg_settings: List[Dict],
+        active_symbol: str,
+        save: bool = True
+    ):
+        """"""
+        if name in self.spreads:
+            self.write_log("价差创建失败，名称重复：{}".format(name))
+            return
+
+        legs: List[LegData] = []
+        for leg_setting in leg_settings:
+            vt_symbol = leg_setting["vt_symbol"]
+
+            leg = self.legs.get(vt_symbol, None)
+            if not leg:
+                leg = LegData(
+                    vt_symbol,
+                    leg_setting["price_multiplier"],
+                    leg_setting["trading_multiplier"]
+                )
+                self.legs[vt_symbol] = leg
+
+            legs.append(leg)
+
+        spread = SpreadData(name, legs, active_symbol)
+        self.spreads[name] = spread
+
+        for leg in spread.legs:
+            self.symbol_spread_map[leg.vt_symbol].append(spread)
+
+        if save:
+            self.save_setting()
+
+        self.write_log("价差创建成功：{}".format(name))
+
+    def remove_spread(self, name: str):
+        """"""
+        if name not in self.spreads:
+            return
+
+        spread = self.spreads.pop(name)
+
+        for leg in spread.legs:
+            self.symbol_spread_map[leg.vt_symbol].remove(spread)
+
+        self.write_log("价差删除成功：{}".format(name))