Abstract: The cylinder liner of a gasoline engine cracked frequently. The causes of cracking on cylinder liner were analyzed by means of macro observation, metallographic examination, chemical composition analysis and hardness test. The results show that the engine cylinder liner cracked under overload during use.The reason was that in the centrifugal casting process of cylinder liner, the wall thickness and cooling rate were not uniform, resulting in the uneven shrinkage of each part and mutually hindered, which resulted in large residual stress. At the same time, in the machining process of blank parts, the surface metal produced mechanical stress and thermal stress due to plastic deformation, finally under the action of working load, the cylinder liner cracked and failed due to overload.