The conventional parallel dual model speed adaptive observer has the problem of large delay and low precision when the motor gets started or a sudden load applied. The problems produce a bad effect on the speed control performance of the speed sensorless control system of the induction motor. To deal with the above problems, a reset adaptive observer is proposed to observe the rotor flux, then the rotor speed is obtained from an adaptive mechanism at the same time. And the stability of the system is proved by using the Lyapunov stability theorem. The simulation and experiment results show that, the proposed observer has high precision and good stability, and improves the speed observation performance, especially when the motor gets started or a sudden load applied.