Abstract: This paper mainly analyzes the defect of 110kV green spring 110kV red and green line 151 circuit breaker abnormal tripping. After comprehensive inspection and analysis of the field circuit breaker control loop, it is finally concluded that because the circuit breaker control loop is equipped with redundant tripping nodes, this node has the risk of node short circuit because the circuit breaker K3 relay is not completely closed. After the secondary line is damp, the insulation is reduced and the circuit breaker is misoperated, there is a hidden danger in the operation of the power grid. At the end of the article, it is proposed that after canceling the special low-pressure automatic tripping function of FXT11 circuit breaker, the circuit breaker does not directly accept the tripping command source, and the circuit breaker will not misoperate, so as to improve the power supply reliability of the power grid.