The aim of the present study is to develop a bagging device depends primarily on a cyclone and fits for bagging the wheat chaff during threshing operation. The developed device was constructed in El-Gemeza Agricultural Research Station El-Gharbia Governorate. For obtaining high performance of the developed device; some parameters were tested at different levels such as; air outlet diameter of 50, 90 and 120 cm, mesh holes diameter of 3, 6 and 10 mm latterly thresher air velocity of 14.4, 17.9, 20.1 and 23.6 m/s. The air velocity at air outlet and chaff outlet were measured, also the chaff losses, grain losses, impurity ratio and cleaning efficiency were determined.The highest air velocity at air outlet of 5.4 m/s was obtained at air outlet diameter of 90 cm, mesh holes diameter of 10 mm and thresher air velocity of 23.6 m/s.  The lowest values of air velocity at chaff outlet, chaff losses and grain losses of 0.2 m/s, 0.36% and 0 respectively were obtained at air outlet diameter of 120 cm, mesh holes diameter of 10 mm and thresher air velocity of 14.4 m/s. The lowest value of impurity ratio of 0.03% and the corresponding cleaning efficiency of 97.7% were obtained at air outlet diameter of 120 cm, mesh holes diameter of 10 mm and thresher air velocity of 23.6 m/s.