In the dynamic tracking and sighting system, obtaining the target image with moderate size, clear and stable is the precondition of tracking and aiming the target. In order to realize smooth, flexible and fast effects in the dynamic tracking system, cam structure can be used. The MTF curve of the system reaches greater than 0.6 in the value of 50 lp by optimizing the cam curve by using MATLAB. Aberration is basically balanced and the imaging quality meets the practical application requirements. The structure with servo motor driving focus cam is compact and lightweight. The focusing precision of system can reach ±1.1 μm. Finally, the dynamic target tracking and aiming are realized.