<,正,>, A super-absorbent polymer is prepared by graft polymerizing acrylamide （AM） ontopotato starch using ceric ammonium nitrate （CAN） and N, N′-methylene-bis-acrylamide（bisAM） as an initiator and cross-linking agent respectively, and then subjecting the potatostarch-poly（acrylamide） （PAM） graft copolymer （SPAM ） to alkaline saponification. Thewater absorbency （WA） of the sample is nearly 5000 g H,2,O/g for dry sample in 24 hat room temperature and is far larger than that of reported in the literature. Thevariables affecting the WA were investigated and optimized, they were: concentrations ofpotato starch, AM, CAN and bisAM were 26.3 g/L, 1.14 mol/L, 10.3 mmol/L and 0.53mmol/L, respectively. The amount of sodium hydroxide was 15 g and the temperatures ofgraft copolymerization and saponification reactions were 60℃ and 95℃. The time of graftcopolymerization and saponification reactions was 2 h, respectively.