Abstract: The influences of electroless Ni-P coating on fatigue property of spring steel were studied by comparative tests,and the mechanism was analyzed.The fatigue life of base materials is the longest in all conditions.Compared with fatigue life of base materials,the fatigue life of plated specimens is shorter due to hydrogen brittleness.The fatigue life after heat treatment process for dehydrogenization or crystallization decrease observably,owing to the decrease of compresive stress.The fatigue lives after heat treatment of 200 ℃×1 h or 200 ℃×3 h are similar.