Underwater laser communication has significant technological advantages over traditional underwater wireless communication methods such as acoustic, long-wave, and very-long-wave communication. However, the underwater environment makes the signal spot vulnerable to deformation and flicker, thus hindering the establishment and maintenance of a reliable optical link. To overcome this problem, we devise an underwater spot tracking software design approach based on Qt and MATLAB mixed programming. The approach adopts the Mean shift iterative algorithm for underwater spot target recognition and localization. A mixed programming method of MATLAB and Qt is used to create the software interface, build a water tank experimental platform, and import the spot photographs. Spot target recognition and movement trajectory drawing are realized using the software, thus verifying the effectiveness of the algorithm. The final result is essentially consistent with the actual spot trajectory, and the maximum error offset is 7.28 pixel.