The bandwidth testing of a beam stabilization system based on a four-quadrant detector is discussed in detail. At first, the working principle, importance, and main application scenarios of the beam stabilization system are introduced. And then, a detailed explanation is given on the working principle, advantages, and application of beam inclination sensors, especially four quadrant detectors, in beam stabilization systems. Next, a detailed introduction to the composition, working principle, and importance of beam stabilization systems in practical applications are provided. In the system testing section, a detailed description of the testing environment, methods, and analysis of the testing results are provided. The testing results indicate that the beam stabilization system based on the quadrant detector has an effective suppression bandwidth of 138.35 Hz for the X-axis and 131.96 Hz for the Y-axis. At last, the testing results are summarized and future work prospects are proposed.