Abstract: The present application provides an engine cooling system, which includes: a coolant pump; a cylinder body (22) and a cylinder cover (24), which include inside coolant passages for receiving coolant from the coolant pump, conduct heat exchange through a coolant outlet of the cylinder head (24), and send parts of the coolant back to the coolant pump; a transmission oil cooler (60) for receiving parts of the coolant from the cylinder head (24), and allowing the parts of the coolant to flow back to the coolant pump after heat exchange; the cylinder head (24) includes an upper water jacket and a lower water jacket, a temperature of the coolant output by the upper water jacket of the cylinder head is higher than a temperature of the coolant output by the lower water jacket of the cylinder head.