In two-step phase-shifting digital holography, the elimination of the zero-order image and conjugate image is directly affected by the phase-shifting error. To eliminate the phase-shifting error and obtain the actual phase-shifting value, the two-step phase-shifting iterative algorithm is presented, based on the statistic property of the phase distribution of the diffraction field in recorded plane. In this method, the initial phase-shifting value is calculated directly from the holograms, and then the sum of the intensity bit errors between the reconstructed image and the holograms is taken as an evaluation function for an iterative algorithm to find the actual phase-shifting value. With this method, any unknown actual phase-shifting value can be found out, so the zero-order image and conjugate image are effectively eliminated, and the quality of the reconstructed image is enhanced. The feasibility and validity of this method are demonstrated by theoretical analysis and optical experimental result.