Abstract: The AA-AM co-polymerization water retaining agent which can absorb 2.414 kg/g deionized water was synthesized by using ⁶⁰Co γ-radiation polymerization. The water retaining agent’s properties, such as the properties of absorbing the 0.9% NaCl solution and the artificial urine as well as the water were examined. The influence of particle size to water absorption rate and absorbance was studied. The result indicates that AA-AM water retaining agent has the excellent liquid-absorption capability, and the larger the particle size of water-retaining agent, the better the liquid-absorption property.