Among all the present phase unwrapping algorithms, the main idea is to get the real phase directly. However, the meaning of phase unwrapping coefficient k is rarely taken into account. A new algorithm to gain directly the value of k based on least-square (LS) phase unwrapping algorithm is proposed. It can unwrap the phase more rapidly and accurately. On this basis, a new phase unwrapping method is put forward. It not only improves the accuracy of phase unwrapping, but also reduces the time of phase unwrapping and accelerates the running speed of the program. Experiments show that the algorithm is feasible. It provides a new way for large amount of calculation in phase unwrapping with high speed and precision.