Using 2-acrylamide-2-methylpropionic sulfonic acid (AMPS), acrylic acid (AA) and guar gum (GG) as raw materials, N, N-methyl bisacrylamide (NMBA) as crosslinking agent, a copolymer resin of AMPS/AA/GG was prepared by ultrasonic irradiation polymerization and the corresponding thermal degradation behavior was also studied by TG. The results showed that under the optinized condition, the water absorbency of the resinwas the largest and the resin had an excellent thermal stability and good retention ability. The activation energy, lg A and reaction order n were 164.29 kJ/mol, 13.84 and 1/6 respectively by kinetics methods and the thermal degradation process followed the random nucleation and subsequent growth mechanism.