The current U-type double pendulum conveyor chain can realize automatic continuous and efficient production,wide range of speed regulation and large angle of slot into and out of the groove has been mature application in many car coating workshops,but in the actual use process due to the subtle changes in the field working conditions and improper maintenance methods,or there will be such as the swing rod and the entrance and exit of the delivery roller is not synchronized and the swing rod chain itself is not synchronized leading to the skid conversion failure,body drop groove,electrophoresis fire and foreign body card chain and other faults,to bring a more serious impact on production.In this paper,through inepth analysis of these faults,the true cause was found out,according to different situations to take corresponding effective measures,and the problems were solved.