The invention discloses a mounting system of an acoustic emission sensor of a bogie, and relates to the technical field of nondestructive inspection of railway vehicles. The mounting system comprisesa rack, a transverse moving structure and a vertical arm frame, wherein the transverse moving structure and the vertical arm frame are arranged on the rack. The vertical arm frame can move transversely along a guiding rail on one side of the rack under driving of the transverse moving structure. The vertical arm frame is provided with a longitudinal moving structure and a sliding table. The sliding table moves longitudinally along the vertical arm frame under driving of the longitudinal moving structure. A polishing and dust-removing manipulator and a sensor pickup manipulator can be mounted on the sliding table. The function of polishing surface layers at any position of the length and height directions of the whole bogie and the function of collecting and purifying debris such as iron rust and oil paint and dust are achieved by using the polishing and dust-removing manipulator; and the function of mounting a sensor at any position of the length and height directions of the whole bogie and the function of automatic dismounting and resetting are achieved through the sensor pickup manipulator, so that automation requirements of acoustic emission testing equipment are achieved, and the detection efficiency and detection quality are improved.