Nowadays high thermal efficiency engine is the mainstream of the gasoline engine development, and the control of the design period is strict, which lead to the cylinder head design become more and more difficult. How to get the optimal design of cylinder head quickly is an important research topic by design professionals in the current, which not only meets the performance requirements, but also guarantees the requirement of reliability. The sub-model method is high efficient and high precision in solving the complex problem of stress and strain, which widely used in truss, road, bridge and large container. Using this technology in the local structure optimization of the cylinder head, will shorten the cycle of structure optimization significantly, and get the optimal design of cylinder head quickly. In this paper, Firstly, the cylinder head global FE model was set up. Considering room temperature assembly and hot firing conditions, the cylinder head stress and strain field was obtained. Based on the cylinder head stress field, high cycle fatigue analysis was carried out. There were many areas safety factor below guide line, which mainly appeared in the water jacket and bolt clamping surface fillet. Secondly, validation of sub-model method was checked by comparison the stress between on cutting borders of the sub-model and on same positions of the global model. The relative error is less than 5%, so the cutting borders were satisfied the requirements. Thirdly, on the critical area, using sub-model method and optimization software Tosca, optimization analysis was carried out, which made the high cycle fatigue safety factor to meet the design requirements. The analysis results show that sub-model method can shorten 80% time for optimization calculation, and get more precise analysis results in the meanwhile, which obtain the optimal design of cylinder head quickly and exactly.