The invention relates to a surface gradient cross-linked method of a ultra-high molecular weight polyethylene and the application thereof. The surface gradient crosslinked method of ultrahigh molecular weight polyethylene includes a n ultra-high molecular weight polyethylene surface photoinitiator diffusion step and an ultraviolet light irradiation crosslinking step. In this method, the photoinitiator is diffused deeply into the surface of ultra-high molecular weight polyethylene, the body material shows a gradient cross-linking from the surface to the inside after ultraviolet irradiation so that the whole bulk has a high toughness and the surface there of has a high wear resistance.