A threshing diameter adjustable longitudinal axial flow cylinder structure, comprising a threshing cylinder, a transmission mechanism (2), a diameter adjusting mechanism, and an adjusting steel wire pulling mechanism (4). The transmission mechanism (2) transmits power to various adjusting devices of the diameter adjusting mechanism； the diameter adjusting mechanism connects the transmission mechanism (2), and implements adjustment of the diameter of the threshing cylinder with the threshing cylinder； both the transmission mechanism (2) and the diameter adjusting mechanism are disposed inside an infeed head cylinder body of the threshing cylinder； an adjusting steel wire (201) in the transmission mechanism (2) is pulled by means of the adjusting steel wire pulling mechanism (4) to perform real-time and stepless adjustment of the threshing diameter of the cylinder. The longitudinal axial flow cylinder structure can implement a real-time and stepless adjustment of threshing diameter of the cylinder during a combine operation process, so that threshing clearance satisfies the best threshing working conditions of grains of different categories and different moisture contents. The cylinder structure does not require a downtime, is convenient and fast, and can effectively reduce labor and improve combine operation fluency.L'invention concerne une structure de batteur à écoulement axial longitudinal réglable de diamètre, comprenant un batteur, un mécanisme de transmission (2), un mécanisme de réglage de diamètre et un mécanisme de traction de fil d'acier de réglage (4). Le mécanisme de transmission (2) transmet de l'énergie à divers dispositifs de réglage du mécanisme de réglage de diamètre ； le mécanisme de réglage de diamètre relie le mécanisme de transmission (2), et effectue un ajustement du diamètre du batteur sur le batteur ； le mécanisme de transmission (2) et le mécanisme de réglage de diamètre sont tous deux disposés à l'intérieur d'un corps cylindrique de tête d'a
