Transport of intensity equation (TIE) is one of the important methods for non-interferometric phase retrieval. Traditional methods are restricted by the shape of the input image or the convergence speed, which limits the universality and phase recovery efficiency of TIE. Therefore, a TIE phase retrieval method based on fast iterative finite difference method (FIFDM) is proposed. On the basis of the TIE solution method based on the finite difference method (FDM), the correlation of each point in the iterative process is considered and the relaxation factor is introduced in FIFDM to realize the phase retrieval. Simulation and experimental results show that, compared with discrete cosine transform (DCT) method and FDM, the proposed method has faster recovery speed, higher accuracy and stronger anti-noise performance.