The invention relates to the field of medical devices, and discloses a molecular sieve gas separation device, comprising a compressor, a first air inlet pipe, a first pressure pump, a first air storage chamber, a first molecular sieve, a second air inlet pipe, a second air storage chamber, A second molecular sieve and an air outlet pipe group; one end of the first air inlet pipe is connected with the compressor, and the other end is connected with a first branch pipe and a second branch pipe respectively; the first air storage chamber is respectively connected with the A branch pipe is connected to the second branch pipe; the first molecular sieve is installed in the first gas storage chamber; the second molecular sieve is installed in the second gas storage chamber; one end of the gas outlet pipe group is connected to the The second air storage chambers are connected, and the other ends are respectively connected with several air storage tanks. The invention can quickly and effectively realize gas separation, has high work efficiency, achieves the effect of oxygen supply, is more environmentally friendly, can be recycled, and saves costs.