以市售的劣质食用油为原料、KOH为催化剂酯交换反应制备生物柴油，研究了反应条件温度、时间、醇油物质的量之比和KOH的用量对生物柴油得率的影响。结果表明：随着温度的增加，生物柴油得率先增加后降低，反应温度为65 ℃时，得率最高，达92.6%；反应1.5 h后，生物柴油得率达89.2%，继续延长反应时间，得率增加缓慢；醇油物质的量之比对得率的增加影响较小，过大还会降低得率；KOH用量为0.8%，生物柴油得率最高，可达92.9%，继续增加KOH用量，得率降低。通过单因素实验和正交实验分析，得出了制备生物柴油的最佳条件：反应温度65 ℃、反应时间2 h、醇油物质的量之比为6:1、KOH用量为0.8%。

KOH catalyzed transesterification of inferior cooking oil was investigated for biodiesel production. The results showed that biodiesel production yield was increased at first and then decreased with increasing the reaction temperature, which reached the maximum value 92.6% at 65℃. The biodiesel yield can reached 89.2% when reaction time was of 1.5h. Further increasing the reaction time above 1.5 h led to only slightly increase in the biodiesel yield. Ratio of methanol to oil has a slight effect on biodiesel production and the optimal KOH dosage was 0.8%, with which 92.9% of biodiesel yield can be obtained.