A gas inhalation device enabling constant concentration of gas entering a respiratory tract without respiratory resistance, said device consisting of a mask (1), a gas source (11) and a gas mixer (10)； the mask (1) is an open mask capable of containing 50-1000 ml of gas, a proximal end of the mask (1) is a soft pad portion (2) which can be fitted to the face, the proximal end of the mask (1) is surrounded by a catheter (14), the catheter (14) being provided with a plurality of small holes (15) in communication with an inner cavity of the mask (1), one end of the catheter (14) being connected to one end of an adapter tube (4), the other end of the adapter tube (4) being connected to a gas supply pipeline (8), the gas supply pipeline (8) being a catheter connecting the adapter tube (4) to the gas source (11) or the gas mixer (10)； a huge hole (20) or a plurality of large holes (9) which are kept open are provided on a distal end of the mask (1), so that the pressure within the cavity of the mask (1) is always zero, and the discharge of gas and exhaled gas from the gas supply pipeline (8) is smooth, almost without airflow resistance； and one or two head belt connectors (5) are provided on two outer sides of the mask (1) and are used for connecting head belts (6) for fixing the mask (1), so as to ensure that the mask (1) is stably fixed on the face.L'invention concerne un dispositif d'inhalation de gaz permettant une concentration constante de gaz entrant dans les voies respiratoires sans résistance respiratoire, ledit dispositif étant constitué d'un masque (1), d'une source de gaz (11) et d'un mélangeur de gaz (10) ； le masque (1) est un masque ouvert apte à contenir 50 à 1000 ml de gaz, une extrémité proximale du masque (1) est une partie de tampon souple (2) qui peut être ajustée sur le visage, l'extrémité proximale du masque (1) est entourée d'un cathéter (14), le cathéter (14) comportant une pluralité de petits trous (15) en communication avec une cavité interne du
