A solution for cylinder wall scuffing is researched. By means of the finite element method, a mathematical model to investigate the temperature field and thermal deformation of the piston is established, which can be used for predicting the cylinder wall scuffing in both the design process of a new diesel engine and the improvement process of the combustion system of an operating diesel engine. The experimental data support the calculated results obtained by using the model. As an application example, the temperature fields and thermal deformations of the piston in the 6E150C diesel engine, which suffers from the cylinder wall scuffing during the period of operation, are analyzed quantitatively by using the mathematical model. After an improved piston with new structure and good cooling system is used in the 6E150C diesel engine, the cylinder wall scuffing no longer occurs. From inspection of the investigation results, it is found that the main factors, which result in the cylinder wall scuffing, are the overhigh temperature of the top compression ring groove of piston and the overextended thermal deformation of piston, and it is believed that the thermal deformation analysis of piston is more important, compared with the temperature field analysis of piston.