Based on the basic principle of four-quadrant-based tracking sensor, the energy detecting rate, centroid detecting error and the displacement sensitivity of four-quadrant detector caused by noise or dead zone are analyzed in detail. The tracking error formula of four-quadrant-based tracking senor is put forward theoretically and verified experimentally. The results show that when the noises are constant, the tracking error of four-quadrant-based tracking senor depends on the ration between the width of Gauss facula and the width of dead zone of four-quadrant detector.