A method of iterative phase retrieval of complex optical field was studied. This method uses a series of diffraction patterns to solve for both amplitude and phase of the object field by using hybrid input-output algorithm. The method requires a phase plate that need transversely rotated to one or more positions. The method needs no a priori knowledge about the object field. The convergence rate was rapid. The simulation results showed this algorithm could fast retrieve a complex optical field in high accuracy. The retrieval accuracy of complex optical field was greatly enhanced. The method does not suffer any stagnation or ambiguity problem, and it has high stability towards additive noise.