The working environment of the diesel valve cam is relatively harsh,during the working process,the working conditions such as the load,speed and radius of curvature between the interfaces change periodically,resulting in harsh lubrication contact conditions and poor wear.The typical working condition of the valve cam mechanism of a marine diesel engine was taken as an example,for the common wear problems of the camtappet,the cosineconstant speed section and highorder pentathine were used to optimize the design of the cam profile,the dynamic contact and elastohydrodynamic lubrication of camtappet pair were analyzed.The results show that the reason for the wear of the original cam is that the dynamic contact stress fluctuates significantly during the movement period of the camtappet pair,and the maximum value exceeds the allowable stress value.After the optimized design of the profile,the dynamic contact stress of the camtappet is reduced below the allowable value,which improve the dynamic contact characteristics.The cam profile has good lubrication characteristics and can maintain a stable oil film lubrication state during operation.The change of cam speed and contact load will directly affect the lubrication state of camtappet,especially with the increase of cam speed,the lubrication film thickness is increased,the pressure is decreased and the lubrication contact state is improved.