The preparation of biodiesel from microalgae lipid oil by two-step catalyzed process was studied.The chemical composition of microalgae oil extracted from oleaginous Scenedesmus sp.was analyzed.The results showed that the free fatty acid accounted to 10%-32%, and total polar lipid accounted to 21%-46% of extracted lipid.Using high acid value and high polar lipid content oil feedstock, the biodiesel was prepared by two step esterification/transesterification catalyzed process.