The primary and secondary order and influencing laws of each heat transfer boundary affecting the wall temperature of the fire plate of cylinder head were found out based on the plate heat transfer theory and orthogonal test method. The research conclusion could be applied to the design of cylinder head, which provided the direction and reference for thermal load control. In the research and development process of a certain cylinder head, the primary control parameter was the thickness of fire plate and the optimal value was determined based on the lowest temperature aim of fire surface. In addition, the feasibility and accuracy of plate heat transfer theory was verified in exploring the temperature laws of fire plate.