Abstract: The production of biodiesel from abandoned animal fat catalyzed by solid catalysts can realize the catalysts reutilization, decrease the cost of raw materials, thus enhancing the market competitiveness of biodiesel. The transesterification reaction of beef tallow and methanol to product biodiesel using Cs2O/γ-Al2O3 as solid catalyst was studied in this study. Response surface methodology and Box-Behnken experimental design were employed to optimize the reaction conditions. The variables of the molar ratio of methanol to oil, catalyst amount, reaction time and reaction temperature were investigated, and the optimum conditions were obtained: molar ratio of methanol to oil 10.5:1, catalyst amount 5.3% (based on the weight of oil), reaction time 120 min, reaction temperature 66℃. Under this optimum reaction conditions, the biodiesel yield was 95.5%. The collected catalyst can be reused after being calcined for 4 h at 400℃ and the biodiesel yields decreased less than 6% after the catalyst being reused for eight cycles in the repeated experiments. The results would offer experimental foundation for the continuous and industrial production of biodiesel catalyzed by solid catalysts from abandoned animal fat, and provide references for improving the market competitiveness of biodiesl.