To establish and verify the design space of ethanol extraction process of Salvia miltiorrhiza.Method：The extraction ratios of cryptotanshinone and Tanshinone IIA are identified as the critical quality attributes(CQAs)，and ethanol concentration，ethanol amount，decoction time are identified as critical process parameters(CPPs).The central composite design is used for experimental arrangements，and the design space of ethanol extraction process of Salvia miltiorrhiza is established based on the quadratic polynomial regression model.Result：Since the p-values of both models are less than 0.05 and values of lack of fit are more than 0.1，the relationship between CQAs and CPPs could be well described by the two models.The reliability of design space，illustrated by overlay plot，is improved with the addition of 95% confidence.Conclusion：The robustness and flexibility of Salvia miltiorrhiza ethanol extraction process have been enhanced via the establishment of design space based on the quality by design(QbD)concept.