The poppet valve always has vibration and noise problems in engineering. Through designing experiments, the poppet valve vibration was observed.It is found that the poppet valve vibration signal is a typical periodic vibration signal. Combining CFD results with the system dynamic models parameters, simulation and analysis about the effects of steady flow force and transient flow force to the poppet valve vibration were made. From the simulation results and theoretical analysis, it is found that the steady flow force is not the reason of valve periodic vibration, and the transient flow force is the main reason of poppet valve vibration.