Abstract: The flux observer seriously influences the stability and accuracy of induction motors. The performance is restricted to the sensitivity of the motor parameters of the traditional open-loop current and voltage flux observer under low or high speed. In order to improve the accuracy and stability of flux observer, a novel close-loop flux observer is implemented, which includes the current and voltage flux observer cooperated with phase-compensated transition function. The accuracy and insensitivity to motor parameter are insured in the whole speed range. The deadbeat stator current observer is added to solve the one sample cycle delay. By the observer characteristic function being utilized to analyze flux observer, along with the simulation and experiment, the accuracy and stability are verified.