A threshing and separating device (10) comprises a first threshing and separating mechanism (1), a second threshing and separating mechanism (2), and an intermediate feeding mechanism (3) therebetween. The first threshing and separating mechanism (1) comprises a first cylinder (11) in a form of a toothed rod and a first concave (12) in a form of a wire-grate, and a surface of the first concave (12) facing the first cylinder is provided with no part protruding into a tip circle of threshing teeth (14) of the first cylinder (11) the second threshing and separating mechanism (2) comprises a second cylinder (20) in a form of a toothed rod and a second concave (232) in a form of a wire-grate, and a surface of the second concave (232) facing the second cylinder is provided with no part protruding into a tip circle of threshing teeth (234) of the second cylinder (20) the second cylinder (20) comprises a forced feeding portion (21) located at front end thereof and comprising a truncated cone (215) and helical blades (214) on the truncated cone and a toothed-rod cylinder portion (23) located behind the forced feeding portion and comprising a plurality of second rods (233) parallel to the rotation axis of the second cylinder and uniformly arranged in a circumferential direction thereof, and each second rod is provided with a plurality of second threshing teeth (234).
