Abstract: Process optimization on the sedimentation rate of Agriophyllum squaarrosum and Sozamnmuiiatnm composite yogurt was investigated using Plackett Burman design, steepest ascent design and Box-Behnkens composite design.Firstly, Plackett Burman ( PB) design method was used to evaluate the effect of six factors which affect the rate of sedimentation of Agriophyllum squarrosum and Sozamnmuiiatnm composite yogurt. Then the center points of the two factors were determined based on steepest ascent design.Then the optimization of the two factors was carried out by using Box-Behnkens composite design. The results showed that the best production process parameters were as follows:The amount of Agriophyllum squarrosum extract was 6.6%, Sozamnmuiiatnm juice was 11.8%, sugar was 7.2%, the inoculum size was 4.2%.The sedimentation rate was 58.69%.Which was in good agreement with the predicted one of 59.29%. In conclusion, the optimized process had good reliability.The Sozamnmuiiatnm and Agriophyllum squarrosum composite yogurt has uniform texture, delicate lubrication and sweet taste.