Aiming at establish accurate dynamic modeling in the research of fault diagnosis of shell transfer arm, research on main parameter identification method of shell transfer arm’s equivalent model. The mathematical model is established on the equivalent model of shell transfer arm, and the time series similarity evaluation method is established. The PSO algorithm is used to identify the main parameters in model. The results show that the accuracy of PSO in the main parameter identification of the shell transfer arm's equivalent model can achieve 1.1% and 1.4%. It can provide key parameter in the dynamic modeling of shell transfer arm.