Recent investigation has shown that the permanent magnet synchronous motor （PMSM） goes chaos for certain parameter values or under certain working conditions, which threatens the secure and stable operation of the motor. Hence, it is significant to study the method of controlling or suppressing chaos in PMSM. Based on LaSalle invariant theory, an adaptive law of controlling chaos was presented in this paper, which enablcs avoiding the influence of undeterministic equilibrium of the system. Simulation results show that the designed control method is effective and its control property is better than that of others. Our research results may help to maintain the system’s secure operation.