A new algorithm called spots regression is presented to solve the tradeoff between the dynamic range and sensitivity of Shack-Hartmann wavefront sensor. This new algorithm allows spots to wander, so the dynamic range can be extended while the sensitivity is also sensitive. In order to find out the relation between the spots array and microlenses array even if spots leave their original sub-aperture, firstly, getting the irregular spots to their primary positions, secondly, finding out the match relation between one spot and one microlens. Finally , all spots and all microlenses match each other. The advantage of this algorithm is that there are no requirements for extra hardware, multiple measurements or complicated algorithms. A simple experiment is carried out to demonstrate its implementation. The results of this experiment are very closed to the theoretical ones. And the dynamic range is 25 times larger than that of conventional algorithm.