Abstract: Experiments and computational fluid dynamics (CFD) simulation were used to analyze the effects of the number and the diameter of oxygen supply ports, the flow rate and the mode of oxygen supply, and different modes of air flow (up-inlet and down-outlet on the same side, or on the different side) on the indoor oxygen enrichment characteristics and the effect of anoxic conditions in a closed buildings with or without air conditioning. Without air conditioning, the number and the diameter of oxygen supply ports, the flow rate and mode of oxygen supply, and formed oxygen-enriched regions are quite different. Using a double-45°-opposite oxygen supply ports with a diameter of 6 mm is advisable. Under the air conditioning condition, the number and the diameter of oxygen supply ports, the flow rate of oxygen supply, and the modes of air flow are different too. The formed oxygen-enriched area are all generally elliptical. It is advisable to use a single oxygen supply port with a diameter of 6 mm and an air flow mode of up-inlet and down-outlet on the different side. When the flow rate of the oxygen supply is the same, the oxygen-enriched area are formed by the wind speed of 0.85 m·s^-1 is approximately 20% larger than that formed by the 1 m·s^-1 wind speed. When the air supply wind speed is 0.85 m·s^-1 and the oxygen supply flow rate is 1.5 m³·h^-1, the oxygen-enriched area is approximately 0.96 m², which is consistent with the area of the single-person activity. It is suitable as the basic oxygen-enriched supply for the single-person under air conditioning conditions where are lack of oxygen.