The invention provides a threshing cylinder shaft assembly and belongs to agricultural machinery. Four rows of abrasion-resistant threshing kneading blocks are evenly distributed and fixedly arranged on the circumferential outer surface of the grain feeding side of a threshing cylinder shaft in the axial lead direction and overall arranged in a double-end double-helical-line shape in the circumferential direction. Six rows of abrasion-resistant threshing separation spike teeth are evenly distributed on the circumferential outer surface of the grain discharging side of the threshing cylinder shaft in the axial lead direction and overall arranged in a three-end three-helical-line shape in the circumferential direction. The assembly is scientific and reasonable in structure, good in threshing separation effect, long in service life, high in adaptability and small in grain entrainment loss.