Abstract: To establish the extraction technology of pharmaceutical excipients steviosin from the leaves of Stevia rebaudiana bertoni. The extraction process was optimized through L9 (34) orthographic experiment designed by selecting the yield and content of steviosin as the analysis indexes. Extract was further purified, and the purification process was optimized and evaluated. The optimal process conditions were as follows:Stevia rebaudiana bertoni was recirculated with 90% ethanol for 3 times, the first time was with 8-fold amount of Stevia rebaudiana bertoni for 2h, the second time with 6-fold amount for 1.5h, and the third time with 5-fold amount for 1h. After ultrafiltration, the extract was further purified by adsorption and desorption with the cation or anion ion exchange resin, following by 0.3BV/h 50% ethanol to elute, respectively, then precipitated steviosin with 80% ethanol for 24 hours. By using this method, the steviosin in the product could reach above 95.0%. Besides, the optimized method was stable, feasible and suitable for industrial production.