Abstract: This paper is based on the principle that the pole of a band-pass filter and the zero of pure integrator offset each other at the origin to improve the voltage model. The rotor flux estimation of the induction motor is accurate. However, the improved voltage model still has the disadvantages of poor performance and low speed. Thus, the current model combined with the voltage model flux observer is proposed to construct a combined model flux observer. The parameters of the piecewise function are derived through a simulation experiment, and the combined model flux observer performed efficiently on the basis of the flux observation results. The simulation model of the combined model rotor flux observer is built in the Matlab/Simulink simulation platform. Simulation results show that the error curve of the combined model is coincident with the error curve of the two observer models at low and high speeds. However, the error curve of the combined model in the transition phase of speed is between that of the voltage model and the current model. Experimental results show that the combined model can accurately calculate the rotor position and has good dynamic response.