The catalytic activity of four liquid organic amines, triethylamine (TEA), diethylamine (DEA), ethylenediamine (EDA) and monoethanolamine (MEA), in the transesterification reaction of rapeseed oil in supercritical methanol was studied in this paper. The results showed that the order of the catalytic activity was DEA > TEA > MEA > EDA. The effect of the molar ratio of methanol to oil on the reaction was involved. Further, with TEA as the catalyst, the effect of the reaction pressure on this reaction was investigated. Pressure had a positive effect on this reaction. Additionally, the efficiency of the co-solvent, including ethyl acetate, propylene oxide, tetrahydrofuran and cyclohexanone, was studied, showing that ethyl acetate had a positive effect on this reaction. The overall results suggested that the methyl ester yield in a continuous reactor was inferior to that in a batch reactor, mainly because of the poor mutual solubility between the oil and methanol. Furthermore, possible mechanisms for this amine-catalyzed reaction were proposed.