Acrylic acid(AA)-acrylic amide (AM) copolymer resin with high absorbency of water was polymerized with acrylic acid, acrylic amide and sodium hydroxide in the free of any cross-linker and initiator under UV irradiation by use of a high- pressured ultraviolet mercury lamp. The influences of monomer ratio, neutralization degree, irradiation time and resin size on the water absorbency performance of synthesized copolymer was investigated. The parameters of resin synthesized in optimum condition are as follows, the deionized water absorbency is 3062 g/g, the saline water (0.9% NaCl) absorbency is 241 g/g, tap water absorbency is 232 g/g, the artificial blood absorbency is 367 g/g, and the artificial urine absorbency is 76.6 g/g.