The invention provides an engine cooling system, an engine and a vehicle. The engine cooling system comprises a first cooling liquid circulating branch, a second cooling liquid circulating branch and a third cooling liquid circulating branch, wherein the first cooling liquid circulating branch is composed of a cooling liquid pump, a water jacket, a thermostat and a heat dissipater, the second cooling liquid circulating branch is composed of a cooling liquid pump, a water jacket, a thermostat and a warm air heat dissipater, and the third cooling liquid circulating branch is composed of a cooling liquid pump, a water jacket and a thermostat. Each thermostat comprises a main valve, an auxiliary valve, a first normally-open port and a second normally-open port. The main valves are opened when the temperature of cooling liquid reaches the first temperature, closed when the temperature of the cooling liquid does not reach the first temperature and connected with the heat dissipaters. The auxiliary valves are opened when the temperature of cooling liquid does not reach the first temperature, closed when the temperature of the cooling liquid reaches the first temperature and connected with the cooling liquid pumps. The first normally-open ports control the second cooling liquid circulating branch to keep a normally-open state and are communicated with the warm air heat dissipater. The second normally-open ports are communicated with the water jackets. The engine cooling system can provide sufficient air-conditioning warm air, the comfort of driving is improved, the operating temperature of the cooling liquid is high, and the fuel economy is improved.