Abstract: In order to meet the structural requirements for threshed tobacco strips set by the new edition of Technical Specification for Cigarette, mixed orthogonal tests and sequential quadratic programming were used to study the effects of threshing with rhombic, hexagonal, circular and papiliform openings of different sizes at different rotational speeds of a threshing drum. The results showed that:1)Adopting the frame basket with hexagonal openings could effectively reduce the percentage of strips with >25.4 mm, increase the percentage of strips of 12.7-25.4 mm, and reduce the stem content. 2)When 9 000 kg/h threshing and redrying line adopted three sets of frame baskets with 2.75-inch(H₀=69.9 mm)rhombic openings and one set of frame baskets with 3.5-inch (A=88.9 mm) hexagonal openings in the first stage threshing and the rotational speed of threshing drum was controlled at 560-660 r/min, the threshed strips could meet the requirements for the large-sized strip percentage < 45%, the large and medium-sized strip percentage ≥ 80% and the stem content < 1.5%.