The invention belongs to the field of civil oxygen generation, and particularly relates to a molecular sieve oxygen generation mechanism. Most oxygen generators sold in the market have the problems that interior structures are complex, hoses are in a mess and assembly efficiency is low. The molecular sieve oxygen generation mechanism comprises a first molecular sieve cylinder and a second molecular sieve cylinder, an upper cover is arranged on the upper side of the first molecular sieve cylinder and the second molecular sieve cylinder, and a lower cover assembly is arranged on the lower side of the first molecular sieve cylinder and the second molecular sieve cylinder; the upper cover is provided with a gas inlet joint, and gas is guided into the first molecular sieve cylinder and the second molecular sieve cylinder separately through a distribution valve. Complicated gas pipelines in an oxygen generator are reduced; connection hoses between the distribution valve and the molecular sieve cylinders and a silencer are omitted, connection hoses between the molecular sieve cylinders and a pressure stabilization cylinder are omitted, a hose for installing a washing calibration hole is omitted, and the washing calibration hole is directly inserted in the upper cover in injection molding of the lower cover as an insert.