The invention discloses a diagnosis and improvement method for low-frequency abnormal sound of an air conditioning compressor under an idling working condition of a blade electric vehicle. The diagnosis and improvement method mainly comprises the following steps that abnormal sound sources are analyzed, and through simulating calculation and spectral analysis, a sound source part is determined preliminarily; then a final sound source part is determined by adopting an acoustic camera imaging technology; then sound source noise analysis is performed, specifically, noise time domain and frequencydomain analysis, sound filter analysis and sound quality analysis are involved; a rotor shaft vibration frequency response test is performed on air conditioning compressors of the blade electric vehicle and a competitive vehicle model, and a structure which generates the noise of the blade electric vehicle is determined; then, a rotor shaft starting control strategy of the air conditioning compressor of the blade electric vehicle is adjusted, and rotor shaft positioning starting is changed to rotor shaft non-positioning starting; and finally, improvement is performed in two aspects of the structure design and the manufacturing machining technology of the air conditioning compressor of the blade electric vehicle. According to the diagnosis and improvement method, the abnormal noise of theair conditioning compressor can be effectively detected and lowered.