The invention relates to an engine cooling system including double expansion tanks. The engine cooling system includes a high-temperature cycle cooling system, a low-temperature cycle cooling system and a delayed cycle cooling system, wherein the high-temperature cycle cooling system comprises a first expansion tank, a high-temperature radiator, an engine cooling water jacket, a first water pump, an electronic thermostat, an engine oil cooler, a turbocharger and a heater; the low-temperature cycle cooling system comprises a second expansion tank, a low-temperature radiator, a second water pump, an electronic turbocharger, an intercooler and a BSG. According to the application of the invention, the two sets of cycle cooling systems are arranged, and the high-temperature radiator and the low-temperature radiator are arranged in the systems respectively, so that the requirements of different to-be-cooled parts for the cooling temperature are ensured; in addition, the technical scheme of the application does not increase the size of the cooling system.