Recent investigation has shown that the permanent magnet synchronous motor(PMSM) may have chaotic behaviors for cortain values of parameters or under certain working conditions,which threatens the secure and stable operation of motor-driven.Hence,it is important to study methods of controlling or suppressing chaos in PMSM.Using the exact linearization theory of differential geometry,a law of controlling chaos in PMSM is deduced in this paper, and then,the process of controlling is simulated and analyzed.Theoretical analysis and simulation results show that the deduced control law is effective and its control property is better than that of other methods.Our results may help to maintain the system's secure operation.