According to the requirements proposed by the world that the wind energy conversion systems must have the capability of low voltage ride through (LVRT), this paper studies the influences to the doubly fed induction generator (DFIG) under grid fault. Based on the DFIG characteristics during the grid fault, this paper proposes control strategy for LVRT of doubly fed wind power generation system based on flux tracking to restrain the DFIG over current effectively. In terms of theoretic analysis, the mode of flux tracking control strategy is constructed, and is simulated in the platform of MATLAB/SIMULINK. The results demonstrate the viability of this control strategy.