Abstract: Wave-shaped springs for motors, made of 65Mn steel, fractured during operation. Physical and chemical methods such as macroscopic observation, electron microscope energy-spectrum examination, chemical composition analysis, hardness inspection and metallographic structure analysis were used to analyze the fracture causes of the wave-shaped springs. The results show that the wave-shaped springs suffered from hydrogen-induced delayed brittle fracture. The fracture surface examined by electron microscope energy-spectrum is a brittle one, with chicken-claw-like patterns visible. The chemical composition of the matrix meets the requirements of 65Mn steel, but the hardness is at the upper limit of the process requirements, resulting in relatively high brittleness of the material; the hydrogen removal in the cadmium-plating process is not timely and thorough, causing hydrogen to diffuse into the matrix and the material to have hydrogen-embrittlement fracture. Therefore, it is recommended to adjust the heat-treatment process of the wave-shaped springs so that the hardness value is at the middle-lower level of the technical requirements, and to control the hydrogen-removal interval time after surface cadmium-plating and extend the hydrogen-removal time.