The shortcoming that the iterative Fourier transform algorithm (IFTA) is sensitive to initial phases is discussed. An improved IFTA algorithm with the initial phases generated by the pseudorandom phases encoding method is proposed to overcome the shortcoming. The improved method has the merits of fast iterative convergence and higher precision for image retrieval. When the retrieval kinoform generated from the improved algorithm is input into a phase-only liquid crystal spatial light modulator, the expected far-field image is obtained again. A kinoform with the diffractive efficiency of 85% can be generated within 10 loops. As a quick phase retrieval algorithm, it is of value in the fields of phased array laser radar and agile beam steering.