AIM: To use secondary regression coherent design to explore the extraction parameters of fruits of Cnidiunm by supercritical CO_2 extraction. METHODS: Extraction pressure,extraction temperature,isolation pressure,isolation temperature Ⅰ and Ⅱ were viewed as factors. RESULTS: The best technological conditions were: extractive kettle pressure was 20 MPa,extractive kettle temperature was at 40(?C);separate kettle Ⅰ pressure was 15 MPa,separate kettle Ⅰ temperature was at 65(?C);separate kettle Ⅱ pressure was 5 MPa,separate ketle Ⅱ temperature was at 38(?C);CO_2 flow rate was 18 L/H,extractive time was 80 min. CONCLUSION: Under these conditions,the separate rate of the extractives from fruits of Cnidium Monnieri(L.) Cuss.could be(24.03%).Using secondary regression coherent design could naturally react the influence of the rule on the every factor to the goal function.