By using rapeseed oil as feedstock, methanol as esterifying agent, and sodium hydroxide and potassium hydroxide as the catalysts, effects of an orthogonal method on yield of biodiesel were researched. The experimental results showed that the activity of potassium hydroxide was better than that of sodium hydroxide. The best reaction temperature, reaction time, amount of catalyst, and ratio of methanol and rapeseed oil for sodium hydroxide were 75 degrees C, 60 min, 1.0%, and 7:1, respectively. The best reaction temperature, reaction time, amount of catalyst, and ratio of methanol and rapeseed oil were 65 degrees C, 90 min, 1.0%, and 7:1, respectively.