Abstract: Preparation and application of biodiesel by esterification of oils of high acid value catalyzed by p-toluenesulfonic acid supported on activated carbon were studied. Catalysts of TsOH/C-A,TsOH/C-B and TsOH/C-C of different loading amounts were prepared by different methods. Comparing 3 kinds of supporting method and 5 kinds of activated carbon(coal-activated carbon 1#,coal-activated carbon 2#,coal-activated carbon 3#,citric-acid-activated carbon and coconut-activated carbon), the best activated carbon was citric-acid-activated carbon and the optimum kind of supported catalyst was TsOH/C-C. Through orthogonal experiment, effects of influencing factors on esterification yield were studied. Under the optimal conditions: amount of catalyst 10%, reaction temperature 70℃, molar ratio of methanol to acidified oil 28:1, reaction time 2 h, yield of the product could reach 88.8%