Epoxidized methyl-α-eleostearate (EME) is a new kind of plant oil-based epoxidized aliphatic acid ester which starts from Tung oil. Tung oil is a special, but abundant biomass resource in China. A solvent-free synthetic technique for EME catalyzed by cation exchange resin was developed. Experimental results showed that the optimal synthetic conditions for EME were as follows: cation exchange resin dosage 5% (wt, calculated by methyl-α-eleostearate), material molar ratio of methyl-α-eleostearate, H2O2 and CH3COOH 1:5:2.5, reaction duration 3 h and reaction temperature 65 °C. EME epoxy value reaches 6.5% under the optimal preparation conditions. The newly developed green technique features low cost, simple operation, low energy consumption, less pollution, short production cycle and good quality and is promising to be industrialized.