The connecting rod is an important part in the engine cylinder. This paper studied the engine cylinder by using Pro/E and ANSYS and achieved some interest results. It used the Pro/E to establish three-dimensional model of the engine and to simulate on it. It also analyzes the connecting rod of cylinder by using the finite element analysis software ANSYS, its modal analysis method was put forward and the low natural frequency and vibration mode were calculated. The analysis method and the results can provide reference for the dynamic design of the connecting rod, and also provide a method for the fault diagnosis engine system.