In the technology of sensorless vector control, the rotor resistance uncertainty has important influences on the accurate observation of the rotor flux and identification of the rotor speed. The rotor resistance robust observer which has rotor resistance uncertainty suppression on the speed identification is presented. According to the Lyapunov stability theory, a new Lyapunov function is setted, in theory, could ensure the stability of observer in the full speed range, then the rotor speed adaptive law is deduced. Make a comprehensive simulation comparison with the current popular resistance and the rotor speed dual identification method, the studies show that: the proposed rotor resistance robust observer method in the range of speed has a good suppression of rotor resistance uncertainty on the pace of speed identification and a high robustness, as well as its small amount calculation, simple structure, easily meets the performance of real-time, it has more advantage on the engineering application.