The method of calculating and correcting object wave reconstruction errors caused by phase shift errors in two-step phase-shifting interferometry is studied systematically. Based on the principle of random distribution and the amplitude-phase independence of diffractive object wave, the expression of objective wave reconstruction error is introduced and the formula for that in the two-step standard algorithm is deduced. The automatic error correction method is suggested by further analyzing the structures, the characters of those errors caused by phase shift errors, and the objective expression. By the proposed method, the reconstructive amplitude and phase errors can be corrected at the same time through simple operation on the objective complex amplitude reconstructed by the standard two-step method without the additional measurement or the acknowledge of phase shift. The computer simulations are carried out to verify the effectiveness of this method, and the results show that the method is robust and reduces the effect of phase shift error on object wave-front reconstruction by about 2 orders of magnitude. Optical experiments also indicate that this method is effective and efficient.