The 3D model of cylinder head and cooling water channel is built in the Pro / E software, the channel model is trimmed and divided to get the grid correspond with the computational requirements in the ICEM CFD, the fluid solving parameters and boundary conditions and other related information is set in the CFX software, the solid domain and the coupling parameter is set in the ANSYS MFX module, then the temperature field of cylinder head and waterways, wall convection heat transfer coefficient and other information is got. The overall design’s rationality can be known from the temperature field, but between two outlets of the cylinder head, the highest temperature of the cooling water is 363K, it can be known from the flow of the cooling water that this part is not easy to be cooled, further improvement of the cylinder head structure should be made to improve the cooling effect of cylinder head.