Abstract: For the focusing demand of optical platform applied in photoelectric tracking control system, such as theodolite and quantum communication telescope, a low-cost, small-sized and high-precision optical focusing control system on the basis of the guarantee performance and reliability was designed. With ARM and FPGA as the processing cores, PID optical control platform realized focusing control, according to the image-forming principle. We analyzed how to improve focusing accuracy of the optical platform and utilized the buffer operational amplifier extending the signal method to improve focusing control feedback deviation signal precision. Three kinds of feedback signal compensation methods were put forward and their comparison and analysis were done as well. An equal median compensation method was chosen to compensate the potentiometer feedback signal. This method simplified the hardware and software design without affecting the focusing time, improved the focusing accuracy and was with features of low-power consumption, easy implementation, high focusing control precision, low cost and small size. The subjective analysis was done to an image collected from the focusing experiment. The objective criterion was used to confirm the analysis. And the validity of the design was verified. This design was applied to a photoelectric tracking and detecting product, whose full focusing time was about 3 seconds at 1 m-leveled precision. The design was with fast response as well as stable and reliable performance.