Abstract: Using pyridine n-butyl bisulfate ionic liquid as catalyst,the affecting factors of synthesis of methyl palmitate with palmitic acid and methanol were studied.The results showed that the esterification rate got up to the highest when the single factor experiment was with the mole ratio of alcohol to acid of 50∶1,the reaction temperature was of 70 ℃,catalyst amount was of 6% and the reaction time was of 110 min.The variance of the orthogonal showed the primary and secondary affecting factors as follow:the amount of catalystthe reaction timethe reaction temperaturethe mole ratio of alcohol to acid,the optimum reaction conditions were:catalyst amount of 6%,the reaction time of 130 min,the reaction temperature of 70 ℃ and the mole ratio of alcohol to acid of 50∶1.Then we made the verification test under these optimal conditions and draw the conclusion that the esterification rate is up to 98.63%.Analysis of variance showed the level change of the four factors has no significant influences on the esterification rate including the reaction time,the reaction temperature,the mole ratio of alcohol to acid and the amount of catalyst.