Abstract: In order to overcome the problems of poor convergence and integer ambiguity solution in phase unwrapping based on least squares method, an improved method of phase unwrapping is proposed based on unwrapping edge detection in this paper. The unwrapping edge is predicted and propelled by comparing the optimal solutions and suboptimal solution in least squares method. The integer ambiguity of unwrapped phase is detected and extracted through an attempt to use additional phase increment into wrapped phase. The feasibility and accuracy of proposed method is tested and validated by using simulated data and ERS-1/2 InSAR interferogram covering Hong Kong and Shen Zhen area. The testing results show that the proposed method can correctly extract 99.5% phase values from the simulated interferogram with strong noise. The accuracy of phase unwrapping tested on the InSAR interferogram reaches ±0.12rad.