Objective To study the extraction process of Xiaoer Jianpiwentong Piaster. Methods The optimum extraction condition of the volatile oil was screened by L9(3^4) orthogonal design;the optimum extraction times was optimized by univariate analysis. Results The optimal extraction of volatile oil was as follows:soaking for 30 min,adding 6 times of water,extracting for 7 h;optimum extraction for 2 times. Conclusion The extraction process is simp...