Abstract: This article built SVM model of synthesis of ethyl salicylate under microwave on the experiment data ,by using LS-SVM toolbox .Nonlinearity and complex mechanism is showed in the microwave catalytic esterfication, but this I advantage of SVM as well as dealing with small sample.,. By cross validation the sum of square error of the model is 2.93%.The standard PSO optimization algorithm is easy on structure and prone to be carried out ,but may sink into local best when conducting complex problems of higher-dimension .For this reason, PSO is improved in as stochastic PSO. By verifying on test function, the latter algorithm is better in speed and optimization ability ,but may throw the found best solution .Eventually a styptic algorithm in the global region is carried out to optimize the svm model of synthesis of ethyl salicylate under microwave .The best condition is :acid alcohol ratio of 1/11,the power of 402W, catalyst of 3.00 mL and reaction time of 43 min. The corresponding yield is 81.91%.