Based on the vibration theory and the matrix optics theory, the principle of the optical image method to test the beam positioning stability is derived. The test method of beam positioning stability is designed, and the experimental results show that the optical image method can accurately analyze the range of the beam positioning stability error, also can analyze the value and influence degree of vibration frequency of the error, and combined with the accelerometer by the electron test method, the source of the error can be detected in the optical system. The optical-electro test method is reliable, simple and convenient, and has good engineering application value, especially for large optical system.