With a motorcycle engine as the research object, establishes a finite element modal of engine shell based on Pro/E-ANSA. Compares and analyzes the mode parameters and experimental results of the engine shell to verify the feasibility of the modal and the correctness of the test method. Adopts the finite element method to analyze free and constraint mode of the engine shell to investigate its vibration characteristics, and lays the foundation for further structural optimization of engine shell and radiation noise control.