Abstract: 50CrVA springs fractured after assembling for a few days. Then different batches of springs were used but fracture occurred again. In order to find the failure cause of the springs, fracture characteristics observation, microstructure examination, hardness and coating thickness testing were carried out. The results show that the failure mode of the springs is hydrogen embrittlement fracture. The surface treatment bath solution for the broken springs had been newly improved and replaced, but the surface treatment process hadn't change accordingly, resulting in the increase of the effect of hydrogen during the electroplating process, which is the main reason for hydrogen embrittlement fracture of the springs. Besides, uncoaxial assembly and use of the springs promoted stress concentration and the occurrence of hydrogen embrittlement. After process test, appropriate improvement measures were proposed, and springs didn't fracture thereafter.