[Objective]The aim was to study the production technology of biodiesel by waste cooking oil. [Method]Production technology of biodiesel by transesterification of fatty acid in the waste cooking oil with methanol under the catalysis of NaOH was studied. [Result]The optimum technological conditions for making biodiesel by waste cooking oil were as followed:the molar ratio of alcohol to oil was 7:1; the catalyst amount accounted for 1.0% of material oil quality; reaction temperature was 60 ℃; and reaction time was 90 min. Conversion rate of material under the conditions reached 86.9%. Content of major components in the biodiesel reached 95.71%. [Conclusion]Biodiesel products with good performances could be produced by taking waste cooking oil as material.