Abstract: High voltage circuit breakers is an important switchgear of the power system. For opening and closing within a few mili-seconds, it is highly sensitive with speedy transmission and great reliability. According to statistics, 80 percent of fault of high voltage circuit breakers is caused by mechanical faults. In this paper, considering a circuit breaker with VS1 type spring actuator as the subject, the vibration signal under typical mechanical faults are collected based on some testing, including spring failure, clearance error, cam eccentricity, over the dead point and so on. Then the intelligent model for fault diagnosis for HV Circuit Breaker based on vibration signals is established. The results indicated that fault diagnosis rate is up to 94% .