Abstract: Fuel assembly gripper driving circuit is a key part of the refueling machine. Its reliability has great significance for safety and stability of refueling operation. A number of tripping faults have occurred since the operation of the refueling machine No.1 and No.2 of Qinshan nuclear power plant II, and it has a certain impact on the refueling operation. With gripper driving circuit as the research object, considering the fault phenomenon and the maintenance experiences, the reasons of key components defect were analyzed in detail, the troubleshooting methods and solutions were summarized, and the measures to solve the problem was provided.