In order to address the problem of the magnetic flux voltage model in the model reference adaptive (MRAS) sensorless control method, which is susceptible to internal parameters and external disturbances of the motor, a sensorless control method for induction motors has thus been proposed based on an improved non-singular fast terminal sliding mode magnetic flux observer. Firstly, based on an improved non-singular fast terminal sliding mode, a voltage model magnetic flux observer is proposed, which enables the system to converge globally and quickly with reduced chattering, while effectively enhancing the robustness of the system. Secondly, a DC component compensator based on the orthogonality between back electromotive force and magnetic flux is designed to suppress the integration drift problem brought about by pure integration in the stator magnetic flux observation process, further improving the accuracy of magnetic flux estimation. Finally, simulation and experiments have shown that the proposed strategy can effectively improve the robustness of the system and reduce the integral drift problem caused by DC bias, thus verifying the effectiveness of the proposed method.