Aiming at the problem that the light spot in underwater wireless laser communication is easily deformed， susceptible to turbulence and to be blocked， firstly， the tracking light spot algorithm of Mean Shift combined with unscented Kalman filter and threshold judgment is used to obtain the real-time position coordinates of the tracking light spot. The analysis results show that when the light spot is blocked， deformed or affected by turbulence， the error between actual movement trajectory and tracking movement trajectory are about 2.1%， 4%， and 1.2%， respectively， which verifies the feasibility of the algorithm. A receiver alignment system is built to track the real-time position of the light spot. The real-time alignment of the receiver and transmitter is controlled based on the relationship of the real-time position and the center position. The alignment accuracy of the system is reflected by the deviation between the actual center coordinates and the center coordinates of the light spot obtained by comparing the alignment system. The experiment results show that the greater the angular velocity of the receiver's motion， the smaller the alignment accuracy.