Abstract: Acrylic rosin acid (2-hydroxyethyl acrylate) ester (ARA) was synthesized by acyl chlorination and esterification of acrylic rosin acid, which was prepared by Diels-Alder addition of rosin with acrylic acid. The composition and contents of the ester were analyzed by GC-MS. Then the copolymer of ARA and methyl methacrylate (MMA) was made by miniemulsion polymerization. Physical properties of the copolymer were characterized by means of GPC, DSC, TGA and solvent extraction. Meanwhile the comparison of properties had been done among the copolymer, MMA homopolymer and MMA copolymer. It was found that ARA was composed of esterification products of (2-HEA)-ester with pimaric acid, dehydroabietic acid, abietic acid and two isomers of acrylpimaric acid. ARA is a good crosslinking agent which can copolymerize with most vinyl monomers. The properties of solvent-resistance and heat resistance of the copolymer were improved considerably by the use of ARA. The copolymer of ARA and MMA is insoluble in acetone whose loss rate is 7.5% during acetone extraction. The TG curves is moved as a whole along the direction of high temperature.