Abstract: The maleopimaric acid polyethylene glycol ester (MPE) with kinds acid value were prepared by maleopimaric acid anhydride (MPAD) and polyethylene glycol 200 (PEG200) when ZnO was used as catalyst. Final products were characterized by FT-IR and performance of MPE-based fluxes were investigated. The results showed that the acid value of maleopimaric acid polyethylene glycol ester are 212.5, 178, 125.3, 72.7 mg/g when the mole ratio of MPAD and PEG200 are 1:0.5, 1:1.0, 1:1.5, 1:2.0 and the reaction time was 3 h, 4 h, 7 h,10 h in turn. The maleopimaric acid polyethylene glycol ester shows optimal soldering ability when its acid value is 178 mg/g, and the appearance of soldered joints are regularly and shiny, the spreading ratio to Sn0.7Cu is 75.8%, which is higher than unmodified rosin.