To solve the problems of ET22 Pneumatic Separator for high-speed belt machine, which is easy to deviation and pneumatic separator chamber leakage of large amount of material, two methods were put forward. On the one hand, transformed the fixed type of retaining belt into a movable type to ensure side seal, avoided material into high speed belt conveyor main roller and the driven roller caused by high speed belt deviation, on the other hand in the pneumatic separator chamber installed wind guiding device, and the wind was guided to the end of halftone, through the wind on the halftone back materials anti blowing, reduced Pneumatic Separator material leakage. After improvement, the improved high speed belt deflection device alarm number from the original 16~24 / down to 0~9 times per month, wind positions lower body leakage decreased by 36.2%~66%.