Abstract: According to the problems about the friction wear of the piston and cylinder which results from the piston slapping of engine， the model with the piston， cylinder， piston pin， piston rings and connecting rod was built in the multibody dynamics software AVLEXCITE. The piston slapping dynamics simulation was carried out when the engine oriented parameters and working conditions were input. According to the simulation result data， predicting the piston surface wear trend and analysis of the piston profile change were carried out. It was found that the piston slapping parameters also increase with the increment of the gap between piston and cylinder， and convex piston becomes skewed cylinder piston. The simulation results and the actual observation results are consistent through the contrast.

Key words: engine, piston slapping, dynamics simulation, wear forecast, profile change