Disclosed are a noise reduction device, a pneumatic path comprising the noise reduction device and a respiratory system comprising the pneumatic path. The noise reduction device comprises a tube body (1), a rectifying component (2), a first pneumatic connector (3) and a second pneumatic connector (4). One end of the tube body (1) is detachably connected with the first pneumatic connector (3), and the other end of the tube body (1) is detachably connected or fixed with the second pneumatic connector (4). The rectifying component (2) is disposed in the tube body (1), the rectifying component (2) divides the tube body (1) into a first chamber (5) and a second chamber (6)； the rectifying component (2) comprises a plurality of gas circulation channels (21), the first chamber (5) is communicated with the second chamber (6) through the plurality of gas circulation channels (21). Through the noise reduction device, the noise generated by the blower during the high-speed operation can be effectively reduced while delivered to the patient by the pneumatic path of the respiratory system. Moreover, the noise reduction device can be disassembled, cleaned and disinfected conveniently, and can be reusable.L'invention concerne un dispositif de réduction de bruit, un trajet pneumatique comprenant le dispositif de réduction de bruit et un système respiratoire comprenant le trajet pneumatique. Le dispositif de réduction de bruit comprend un corps de tube (1), un composant de redressement (2), un premier raccord pneumatique (3) et un second raccord pneumatique (4). Une extrémité du corps de tube (1) est reliée de façon détachable au premier raccord pneumatique (3), et l'autre extrémité du corps de tube (1) est reliée ou fixée de façon détachable au second raccord pneumatique (4). Le composant de redressement (2) est disposé dans le corps de tube (1), le composant de redressement (2) divise le corps de tube (1) en une première chambre (5) et une seconde chambre (6)； le composant de redr
