Abstract: Synthesis and characterization of superabsorbent material was studied by grafting copolymerization of rice straw with acrylic acid. The rice straw was first pretreated with alkali, and then grafted with acrylic acid in the presence of complex initiator consisted of persulfate cerium saltNaHSO3. The results showed that lignin and hemicellulose of rice straw was efficiently removed by alkali treatment, and the ash of rice straw was reduced to 1.8%. Meanwhile, the increased relative amount of cellulose and modified fiber tissue structure were found to be benefit for the subsequent graft reactivity. The synergistic effects of the complex initiation system were intensified when the mass ratio of persulfate/cerium salt/NaHSO3 was 15∶3∶5. The grafting ratio and water absorbency of product was 493% and 350 g/g respectively under the conditions of m(acrylic acid)∶m(rice straw)=8∶1, 70% neutralization degree, 1% crosslinking agent dosage and 60℃ for 3 h.