In order to fulfill the requirement of stator flux identification accuracy in the calculation of airgap torque, puts forward a stator flux online identification algorithm based on a new pure integral method, which used mulriple simpson integral model. Compared with the traditional trapezoidal integral method, this model improved the identification precision of the stator flux; while compared with the new stator flux observer based on lowpass filter, it was more simple and easy to operate and implement. Through MATLAB/Simulink platform, a simulation system was built. The results showed that the algorithm eliminate the major drawbacks of traditional integration method and solve the integral saturation and initial value problems. The stator flux estimated used the new algorithm essentially coincident with the theoretical results, showed the higher reliability of the algorithm.