Abstract: The effects of rotational speed of threshing drum in first stage threshing unit and strip outputs (SO) from first to fifth stage pneumatic separators (PS) on the quality of strips were investigated with uniform experiments. The results showed that:1) With the increase of total SO of the unit, the rate of medium size strips decreased significantly, while the rates of stem in lamina and Obj stem (diameter over 2.38 mm) raised significantly. 2) The factors influencing effects on total SO of the first threshing unit and strip quality were in the order of SO of second PS, SO of first PS, SO of fifth PS, rotational speed of threshing drum, SO of fourth PS, SO of third PS. 3) While keeping the rotational speed of the first stage threshing drum unchanged, the total strip output of the unit was mainly affected by the SO from first to third stage PS; the overall quality of strips would be deteriorated obviously when too many strips were discharged from the second PS; however, the effect of SO of third PS on strip quality was not significant.