The influence coefficient and lag phase are applied in research on measuring and diagnosing the phase angle definition of vibration analyzer based on the analysis of rotor dynamics and linear properties of mathematical vector. Firstly, the relationship between the standard pulse signal and vibration is studied by using the influence coefficient method to identify the direction of an unbal anced position. Then, according to the definition of lag angle, the high point of vibration response can be gotten by using the inverse method. The anti-vibrati on phase angle can be calculated, and the relationship between measured phase angle and the anti-vibration phase angle can also be inferred to determine the meaning of synchronous frequency vibration phase. Finally, without the definition of phase angle, the vibration phase measured by LMS test system is carried out. The test result shows that the proposed method is simple and easy to use, which can analyze and diagnose the phase angle meaning of different vibration analyzers effectively.