To establish implant longevity of hip prosthesis in orthopedics, a new approach was proposed to improve dramatically the wear resistance and to reduce the surface friction of the acetabular cup as a bearing material in femoral head.To do so, ultra high molecular weight polyethylene (UHMWPE) and hydroxyapatite (HA) composites with four amounts of HA content were prepared by sol-gel process and the four composites were hot-molded to make a composite with HA gradient content.When the resultant UHMWPE/HA agglomerates by the sol-gel method were molded in the narrow temperature range of 145～153 ℃, the (110) planes with highest density of atoms in the PE crystal unit were oriented predominantly parallel to the resultant film surface.Such an unusual planar orientation contributed excellent wear resistance and low friction on the surface.