Mostly stator flux linkage is obtained by integration of back electromotive force (back-EMF). The initial value and DC bias of the back-EMF can make the integral result deviation seriously. The amplitude and phase relationships of stator voltage, back-EMF and stator flux linkage in three-phase induction motor are analyzed, and a new method is proposed for the calculation of stator flux. This method is simple in theory, easy to be implemented and has small amount of calculation. The MATLAB simulation prove the feasibility and effectiveness of the proposed method.