In order to eliminate the phase jump error of existing phase unwrapping method based on multifrequency heterodyne principle, the improvement of the phase unwrapping method based on multi- frequency heterodyne principle is proposed. The partial fringes unwrapped phase is obtained by using the method of dual frequency heterodyne principle. Then the unwrapped phase is converted to other fringe relying on the relationship between the phase and the fringe pitch. After that, the wrapped phase is corrected by the converted phase, and the unwrapped phase is obtained. A series of constraints in the processing of unwrapping are derived in order to get the accurate and no jumped phase. The simulation and experimental results show that the method is simple and effective, and there is no phase jump in the unwrapped phase. The improvement of time efficiency is over 30% compared with the existing method.