Abstract: The present invention relates to an oil recovery process with composition-adjustable multi-component thermal fluid, the process comprises: adding oxygen produced by air together with fuel and water into a reactor, in which the oxygen and the fuel combust to produce flue gas and heat, the heat heats water to generate hot water/steam, and then the flue gas and the hot water/steam are mixed to form multi-component thermal fluid, wherein the purity of oxygen added into the reactor is controlled so as to produce the multi-component thermal fluid with various mass ratios of flue gas to hot water/steam; then the obtained multi-component thermal fluid with various mass ratios of flue gas to hot water/steam are injected into various types of oil reservoirs for oil recovery. The oil recovery process of the present invention is applicable for various types of crude oil reservoirs.