When system parameters falling into a certain area, the permanent magnet synchronous motor (PMSM) is experiencing chaotic behavior, which threatens the secure and stable operation of drive system. To control the undesirable chaos in PMSM, a new controller is proposed based on tridiagonal structure matrix stability theory. The proposed controller has some advantages: it is very simple and easy to be implemented; the control transition time is very short; it's robust against external interference. Simulation results are presented to show the effectiveness and robust of the controller.