This paper mainly focuses on the phenomenon of occasional shift gap in the driving process of SAIC-GM Chevrolet Chevrolet EMT transmission model cars,mainly to check the possible fault causes in the hydraulic shift operating mechanism,and finally eliminate the fault process through continuous analysis,diagnosis and maintenance.Since this fault phenomenon can also occur in AMT transmission models with hydraulic actuators,this failure analysis is also applicable to the analysis of vehicles using this type of transmission.It is hoped that through this analysis and maintenance,the maintenance personnel who deal with this type of model can be given some help,providing a reference basis for such fault maintenance.