Since the permanent magnet synchronous motor(PMSM) has a large number of parameters and the direct analysis of parameters impact on PMSMs dynamic behaviors is inconvenient, multiparameter unified approach was proposed and all the PMSM’s dynamic behaviors can be discovered through indepth analysis of the unified parameters. PMSM equilibrium local stability condition as well as Hopf bifurcation condition and pitchfork bifurcation condition were derived through the Routh-Hurwitz criterion and the bifurcation theory respectively. Pitchfork bifurcation line together with subcritical Hopf bifurcation line divided the equilibrium parameter plane into three regions, where the equilibrium had different characteristics in different regions. Simulation showed the equilibrium bifurcation characteristics along with single parameter variation, and one pitchfork bifurcation point and two subcritical Hopf bifurcation points were found in the equilibrium bifurcation curve. The PMSM dynamic behaviors along with parameters variation were studied by phase portraits, time history map and Poincaré bifurcation 〖JP3〗diagram, and presented different mechanisms. If there was only one stable equilibrium in the parameters regions, the PMSM can work stably. If there were two stable equilibriums in the parameters regions, the initial conditions would affect PMSM operation. If there was no stable equilibrium in the parameters regions, the PMSM cannot work stably. The research of this paper can provide some references for PMSM design.