The objective of the project is to research the production of biodiesel from fat of Tra Catfish and methanol using KOH/gamma-Al2O3 as a solid-base catalyst. The results show that KOH/ganna-Al2O3 prepared by loading KOH of 7 mmol on Al(OH)3 of 1g, after being calcined at 550°C for 2h, which can give the best catalytic activity for this reaction. The maximum conversion of 92,63 percent has been achieved after 90 minutes, at 60°C when the molar ratio of MeOH to Tra catfish fat is 8/1 and 6 percent KOH/gamma-Al2O3 catalyst. The produced biodiesel met the required ASTM D6751 standard.