An engine cooling jacket structure comprises a cylinder body cooling jacket, a cylinder cover cooling jacket and an air cylinder cushion. The cylinder cover cooling jacket comprises a first cooling jacket, a second cooling jacket and a third cooling jacket. The air cylinder cushion is arranged between the cylinder body cooling jacket and the first cooling jacket. The first cooling jacket is provided with a plurality of transverse cooling channels passing through an air valve nose bridge zone and the periphery of a sparking plug hole. The air cylinder cushion is provided with a plurality of water passing holes. The first cooling jacket is provided with a plurality of water inlet holes corresponding to the multiple water passing holes. The second cooling jacket is arranged below an exhaust manifold. The third cooling jacket is arranged above the exhaust manifold. The second cooling jacket and the third cooling jacket communicate with the first cooling jacket. The engine cooling jacket structure is provided with the parts corresponding to the air valve nose bridge zone, the periphery of the sparking plug hole, the exhaust manifold and other critical zones, in addition, the parts corresponding to the air valve nose bridge zone and the periphery of the sparking plug hole are of a transverse cooling structure, the structure is reasonable, an integrated exhaust engine can be effectively cooled, and the effect that all cylinders are uniform in temperature is ensured.