An oxygen delivery method for delivering oxygen stored in an oxygen tank to a recipient according to an embodiment of the present invention includes: receiving a prescription flow that is an oxygen delivery flow prescribed to the recipient; receiving a saving ratio, the saving ratio being input by the recipient and being a ratio of a prescription flow and an average delivery flow; selecting an oxygen delivery mode among a plurality of preset oxygen delivery modes based on the saving ratio; detecting a breathing pressure of the recipient; and controlling an oxygen delivery flow to the recipient based on the prescription flow, the saving ratio and detected breathing pressure.