In view of the flaw found in the identification of permanent magnet flux linkage for interior permanent magnet synchronous motors, a parameter identification method of permanent magnet flux linkage based on sliding mode variable structure has thus been proposed. Firstly, taking as state variables the product of stator current and inductance in the magnetic field synchronous rotating coordinate system, the state equation for permanent magnet flux identification of interior permanent magnet synchronous motors (IPMSM) can be constructed. Then, a sliding mode observer can be constructed by combining the sliding mode variable structure with the model, followed by the proof of the stability of the observer and the convergence of the flux parameters to be identified by using Lyapunov stability theory. Finally, the feasibility of the method to identify permanent magnet flux linkage for interior permanent magnet synchronous motors can be verified by simulation results.