Abstract: To improve the poor performance of fluid loss additive in high temperature resistance and salt resistance, this paper has introduced a novel monomer which has specific structure. The 2-acrylamido-2-methyl-propanesulfonic acid (AMPS), acrylamide(AM) and JM containing molecular side chain polyoxyethylene(C2H4O)n have been involved in the copolymerization of this filtrate reducer for drilling fluid SJ-1 of which performance has been evaluated. We have also discussed a serial of experimental factors and obtained the optimum scheme of copolymerization, which is, monomer mass is 15%, temperature of reaction is 60℃, dosage of initiator is 0.2%, molar ratio of monomer AM:AMPS:JM is 14:5:1. The results of infrared characterization have confirmed that the structure of our product is consistent with that of what we designed. Moreover, this polymer has shown good temperature resistance (200℃) and salt resistance (salt concentration up to 30%).