Abstract: To solve the problem of wear failure occurred on both sides of the TC4 titanium alloy piston skirt in a high power density diesel engine under standard operating conditions, a microscopic analysis on the wear area of the piston skirt was carried out by combining metallographic analysis, electron microscope scanning and other physical and chemical detection methods firstly. And then, a finite element analysis software ABAQUS was used to conduct a macroscopic research on the stress and deformation of the piston skirt. The microscopic and macroscopic analysis methods were combined to explore the wear failure mechanism of the piston skirt. The results show that the area of maximum piston skirt deformation coincides with the wear area. The analysis results indicate that main reason of the failure is the insufficient stiffness of the piston skirt, deformation occurred under the high temperature and high pressure, and adhesive wear with the cylinder liner. Finally, some improved piston tests were carried out. Improving the main structural parameters of the piston, it can make the skirt deformation less than the predetermined secondary correction value, avoiding the problem of four-point wear on the piston skirt.