A new algorithm of solving angle ambiguity of rolling interferometer based on second-order differential information of phase change curve was proposed and induced, considering the limitation of traditional algorithms that are not applicable to severe ambiguity. According to continuity of cosine function and applying the maximum likelihood criterion, the algorithm the discriminator phase difference information of current point and the former two points, correct ambiguity number of current point. The simulation results show that, compared with traditional algorithms, the new algorithm can be applicable to severe ambiguity. orrectness and effectiveness been verified in.