This paper mainly studies the onboard Pan-Tilt-Zoom(PTZ) visual tracking control system of a mobile robot for moving targets. Firstly, the mathematical modeling of the PTZ tracking control system is carried out. Then, in order to improve the rapidity and accuracy of moving target tracking, a new finite-time visual tracking control algorithm is proposed based on finite-time control technology. Rigorous theoretical analysis proves that the system can track the target in limited time even in the presence of external interference. In other words, by controlling the rotation of the PTZ, the moving target is always in the center of camera's view during the robot movement. The simulation results show that the proposed finite-time control algorithm can actually track the moving target in finite time.