Objective: To investigate the optimal extraction process of effective constituents from Schisandra sphenanthera by central composite design/response surface methodology. Method: Independent variables were ethanol concentration

reflux time and the volume ratio of material to solvent

dependent variable was extraction rate of schisandrin A. Linear and nolinear mathematic models were used to estimate the relationship between independent and dependent variables.Response surface methodology was used to optimize the process of extraction. Prediction was carried out through comparing the observed and predicted values. Result: It was showed that the regression coefficient of second-order quadratic model was as high as 0.956 5. The optimum conditions of extraction process were 62% ethanol

2.5 hours for reflux

11.20 fold solvent and 2 times for extraction.Bias between observed and predicted values was 1.22%. Conclusion: The observed values and predicted one are close to each other

which proved the optimum model is reasonable and predictive.