Methylacrylic acid polyethylene glyco1 ester was synthesized by using methylacrylic acid and polyethylene glycol 400.The factors such as dosage of polymerization retarder,reaction time,reaction temperature,acid glycol molar ratio and the dosage of catalyst on the yield of product was investigated, and the product was analyzed by using 1HNMR and IR.The results show that the yeild of product reached 88.4% at optimal condition of temperature was 100 ℃, reaction time was 8 h, acid glycol ratio was 3∶1. And the mass fraction of opposite-methyl-phenylsulfon was 2.5%.