Abstract: OBJECTIVE To study the relationship between the extraction parameters and quality control indexes of Yangwei granules, to determine the optimal process parameters to improve the extraction efficiency. METHODS The Box-Behnken experimental design method was used to study the correlation between the three parameters of water addition, water volume temperature and decoction temperature in the extraction process of Yangwei granules and the content of paeoniflorin, the quality control index, that is, the investigation of water volume, water addition temperature and decoction. The optimal process parameters were determined by the multiple regression model, and were further confirmed. RESULTS The study revealed that the extraction rate of paeoniflorin in Yangwei granules was directly influenced by water temperature, water volume and decoction temperature. Among these three process parameters, the water volume and decoction temperature have significant effects. Optimal process parameters for the extraction were water temperature of 37.8℃, water volume of four times the weight of medicinal material, and decoction temperature of 94.7℃. An average content of paeoniflorin from three independent experiments under optimized operations was 0.189 2 g·g^-1, which was close to the theoretical value 0.192 4 g·g^-1. It was 37.7% higher than that of non-optimized conditions(0.137 4 g·g^-1). CONCLUSION The quantitative model established in the research is conducive to the precise control of process parameters and to increase the extraction efficiency, resulting in the improvement of the quality of Yangwei granules.