Abstract: This paper presents an improved control strategy for tracking system based on photoelectric sensors. Taking the sun-tracking system as an example, the new three-quadrant position sensor is used to replace the original four-quadrant sensor for finding directions, which reduces the system cost and difficulties of controlling. The improved system control strategy uses the differential effect to reduce the analog quantities to two, corresponding respectively to the two-dimension control of the horizontal and vertical directions. Compared with the original control strategy, the proposed control logic is simpler, thus the real time and reliability can also be guaranteed. Tests explain that the system can realize the tracking of the point light source in the whole airspace and replace the existing four-quadrant sun-tracking system. By replacing the terminal sensor, the improved control strategy can also be used to track electromagnetic wave sources in space, which has great application value in both military and civil fields.