Optimized the key technical parameters of the flexible winnowing machine, to improve the sign out rate and the product purity. By the significant analysis on the main process parameters of equipment, determined the main parameters which influence the whole factor test, and the application of response surface method was used to find the best control model. And applied the model to the actual production after validation, to determine the best parameter combination. Results: Among the three main parameters of flexible winnowing machine technology, for the wind speed, throttle opening and the frequency of needle roller, the wind speed and the throttle opening has a significant influence on the sign out rate. When the wind speed was 19.0 m/s, the throttle opening was 11.5%, the target control could be achieved. When the wind speed of flexible winnowing machine was controlledin 19.0 m/s, and the opening of the throttle was controlled in 11.5%, the sign out rate can be controlled within the 90% target, stable.