Abstract: Circuit breaker refers to a switching device that can close, carry and break the current under normal or abnormal circuit conditions, and is an important switching device in power system. The situation that the circuit breaker can't be closed is basically in the process of closing operation and reclosing. This kind of fault affects the normal work of the equipment and the normal operation of the power grid. Therefore, this paper introduces the cause analysis and rectification of a 10kV circuit breaker closing failure.