In order to solve the problem of abnormal noise in the operation of a large tubular pump station in the South-to-North Water Diversion Project，this article analyzes and introduces the composition and working principle of a horizontal synchronous motor，conducts core pulling inspection on the main motor，and deeply analyzes the reasons for the abnormal noise problem of the main motor. Based on the inspection and cause analysis of the motor，measures such as replacing the bearings at both ends of the motor，grinding the wind deflector，polishing the worn parts of the silicon steel sheet，cutting off the excessively long binding line，and cleaning the cooler pipeline were proposed. After maintenance and repair，electrical tests and trial operation showed that the abnormal noise of the motor disappeared，and the measures taken achieved ideal results. The research results of this article can provide certain reference value for solving the same type of problems with the main motor of the same pump station，thereby continuously improving the design，manufacturing，and daily operation and maintenance quality of the main motor and enhancing the daily maintenance ability of the main motor of the pump station，which is helpful to ensure the long-term safe and reliable operation of the pump station.