Engine cooling system and cooling method

The invention discloses an engine cooling system and a cooling method. The cooling system comprises a water pump, a double-valve temperature regulator, a machine oil cooler, a water jacket of a cylinder body, a water jacket of a cylinder cover, a water tank radiator and an EGR cooler. The cooling system adopts a water passage circulation as follows: when the engine is started, the water pump begins to work; cooling liquid firstly flows into the machine oil cooler and enters in the water jacket of the cylinder cover to cool the key area of the cylinder cover, and then enters in the water jacket of the cylinder body from a gasket circulating hole of the cylinder cover to cool the cylinder body and the EGR cooler. The cooling liquid in the cooling system firstly cools the cylinder cover to reduce the temperature of the cylinder cover by 10 DEG C to 15 DEG C, enhance aeration efficiency, enlarge air inlet quantity, promote complete combustion, reduce the formation of discharge objects andenhance output efficiency; After cooling the cylinder cover, the cooling liquid enters in the cylinder body for cooling the cylinder body; the higher temperature of the cylinder body can reduce friction, improve fuel efficiency, enhance the output efficiency and reduce peak value pressure and temperature in the cylinder.