The permanent magnet synchronous motors (PMSMs) may have chaotic behaviors for the uncertain 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 PMSMs. In this letter, robust stabilities of PMSM with parameter uncertainties are investigated. A novel asymptotical stability criterion is established. Some illustrated examples are also given to show the effectiveness of our results.