Abstract: Methoxy polyethylene glycol monomethacrylate eaters are synthesized from methacrylic acid (MAA) and methoxy polyethylene glycol (MPEG). A composite TN inhibitor for methacrylic acid is prepared beforehand using pretreatment method. Effect of MPEG molecular weight, temperature and reaction time on the esterification are discussed. The TN inhibitor is proved to have excellent inhibition ability to the polymerization of MAA. With 0.75% of TN, MAA does not visible polymerize at 120 ℃ for 20 h. While, MPEG starts to decompose at 140 ℃, where the —OH group is oxidized to C＝O in some extent. The mixture of TN and MPEG is stable at 120 ℃, where the esterification with MAA can be achieved to 99%. The esterification rate decreases with the increase of MPEG molecular weight at the early 4 h, but there is little effect of MPEG molecular weight after 4 h reaction when the esterification rate is above 80%.