The cause of abnormal noise in propeller propulsion system of a self-propelled offshore platform and its transmission path are analyzed by means of test and measurement. By collecting the vibration acceleration of propeller propulsion system components and key points based on their installation at different speeds of the driving motor, the location of the noise source and its main transmission path is realized by using the method of spectrum analysis. The method presented in this paper can be used for reference in similar vibration and noise problems.