The finite element models of the cam and the camshaft were built.According to the working theory of the seat angle adjuster,a simulative contact analysis of the cam and the camshaft with different interference amounts was performed through non-symmetric matrix,the conclusion that contact stress increases with the increase of the interference amount was obtained.Based on the basic theory of interference fit,the theoretical interference amount of 0.031 mm was calculated.The optimal interference amount calculated from the simulation and theoretical results is 0.04 mm,which can provide a more simple method for interference design.