Fluid-solid coupled heat transfer simulation of cylinder head in CNG engine were carried out by using CFD software, the temperature field and the flow field of cylinder head were achieved and investigated. Calculating results were compared with the experimental results in order to validate the veracity of model. Improvements refer to gasket hole area have been presented according to the problems in calculation results. The cooling effect was improved by increasing water flow quantity in the vicinity of fifth cylinder and decreasing the water flow quantity near the first and second cylinders.