Biodiesel, produced by the transesterification of vegetable oils or animal fats with methanol, is a promising alternative diesel fuel. In this study, a series of strong base anion resins with different basicity, pore structure, degree of cross-linking, and particle size were investigated as heterogeneous catalysts for the transesterification of soybean oil with methanol. A trace amount of CH3ONa, functioning as a homogeneous catalyst, was found to exhibit synergetic effects with the resin catalysts. By using this combined method, the transesterification. reaction approached completion after 6 h at 328 K. The reason for this synergetic effect can be attributed to the regeneration of active catalytic sites in a basic environment.