Water cooling system of engine and cooling method thereof

The invention relates to an engine water cooling system and relative cooling method, wherein the first sensor senses the working condition of engine; the cooling liquid temperature sensor senses the temperature of cooling liquid inside the engine; the control unit responds the signals of first sensor and the cooling liquid temperature sensor, to control the electric water pump to operate when the temperature of cooling liquid is higher than the first preset temperature when the engine starts, to drive the cooling liquid to cool the engine, to improve the starting property of engine and the discharging property of heating machine; and the electric controller based on the operation parameter of engine and the temperature of cooling liquid, controls the switch of electric valve, the electric water pump and the rotation speed of electric fan, to control the circulation and the flux of cooling liquid, and the cooling ability of cooling fan, to improve the property of engine.