Flax threshing and cleaning prototype was identified upon the mechanical and aerodynamic separation cleaning theories. The aim of this study is develop a small prototype machine for threshing and cleaning a manual feeding of flax capsules. The performance of the manufacture prototype was test at four peripheral tooth cylinder speeds of 0.40, 0.44, 0.48 and 0.51 m/s; cylinder concave clearance of 2, 4, 6 and 8 mm and air velocity of 1.5, 2.5, 3.5 and 4.5 m/s at recommended seed moisture content of about 14 % d.b. The performance of the modified machine was determined by threshing efficiency, un-threshing capsules, seed damage (visible and invisible), seed losses, seed cleanliness, total seed losses and seed germination ratio. The results showed that the suitable drum speed, concave clearance and air velocity are 0.44 m/s, 2 mm and 4.5 m/s respectively to obtain the best threshing efficiency of 98.45%, seed cleanliness of 92.3% and germination ratio of 91%. Then the modified machine can be used to threshing and cleaning the flax and it can applied the modified machine specifications on the large scale machines.