Biodegradable cellulose was selected as a basic skeleton, using ceric ammonium nitrate as an initiator treated cellulose, the water-absorbent resin was synthesized by grafting copolymerization with acrylic acid by ultrasound-assisted method. The effects of ultrasonic power, initiator concentration, the ratio of monomer concentration to microcrystalline cellulose, degree of neutralization and crosslinking agent dosage on the water absorbency of the resin were investigated, and the water-absorbent resin was analyzed by infrared spectrum and scanning electron microscope. The results showed that the optimal process conditions were as follows: ultrasonic power was 500 W, initiator concentration was 1.8 mL, the ratio of monomer concentration to microcrystalline cellulose was 3.0:2.0, neutralization degree was 50%, and mass fraction of crosslinking agent was 0.10%. Under these conditions, the absorbency of the absorbent resin was 486 times of distilled water and 173 times of tap water. The structure and properties of grafted product were characterized by IR and SEM, and the results showed that the ultrasonic treatment could lead to the change on the surface of the microcrystalline cellulose, promote microcrystalline cellulose and solid phase graft copolymerization of acrylic acid, the synthesized cellulose resin retained respective characteristics of the microcrystalline cellulose molecular skeleton and polyacrylic, a graft polymerization occurred on the cellulose macromolecular surface and the amorphous zone.