Studies were carried out on transesterification of soybean oil with methanol catalyzed by NaOH for the production of biodiesel.The effects of catalyst concentration,the ratio of methanol to oil,the reaction temperature,rate of mixing and methanol grade on transesterification of Soybean oil were researched.The fatty acid methyl esters content in the reaction mixture was quantified by GC method.The results indicated that the optimal conditions for the transesterification of soybean oil were catalyst concentration 1.0%,the ratio of methanol to oil 6∶1,the reaction temperature 65℃,rate of mixing 400r/min.The yield of methyl esters from Soybean oil under the optimal condition was 98%~99%.