Abstract: The phase discontinuity caused by the geometric mutation has always been a challenging problem in phase unwrapping. To solve this problem, a fast discontinuous phase unwrapping algorithm based on orientation and transformation was proposed. In the proposed algorithm, the structure tensor of the image was used to estimate the orientation of the wrapped phase diagram. The reliable weight coefficient diagram obtained from transformation and difference calculation of the orientation diagram was taken as the weight of the weighted least square method, and used the preprocessed conjugate gradient method to solve iteratively. This algorithm could quickly find the discontinuous regions, and performed a separate phase unwrapping in the discontinuous regions, which had good recognition and unwrapping effect. The principle and implementation steps of the algorithm were described in detail, and the algorithm was verified by simulation and experimental data. The experimental results show that the root mean square error of phase unwrapping is 0.36, which proves that this algorithm can quickly and accurately unwrap the discontinuous wrapped phase.