Heavy oil oxygen-enriched fire flooding is an enhanced in-situ combustion technology，which can effectively improve the combustion efficiency of heavy oil by injecting high concentration oxygen. However，there are few studies on the mechanism of heavy oil oxygen-enriched combustion and the kinetic parameters under different oxygen contents. In order to clarify the effect of oxygen enrichment on the oxidation characteristics of heavy oil in-situ combustion，Liaohe heavy oil was taken as an example. The simultaneous thermal analyzer was used to study the thermal weight loss and exothermic characteristics of heavy oil oxidation under different oxygen concentrations and heating rates. Based on the iso-conversional method，the activation energy under different conversion rates and different oxygen concentrations was calculated，and then the improvement effect of oxygen enrichment on in-situ combustion was studied by numerical simulation. The results showed that the oxidation of heavy oil under oxygen-rich environment could still be divided into four stages：pre-low temperature oxidation，low temperature oxidation，coke deposition and high temperature oxidation. With the increase of oxygen dosage from 20% to 100%，the oxidation reaction was more intense，the reaction rate was larger，the heat release increased，and then the corresponding coke deposition stage was advanced by 20 ℃. The change trend of activation energy under different oxygen concentrations was the same. In the low temperature oxidation stage，the oxygen concentration had little effect on the activation energy. While in the high temperature oxidation stage，the response was intense，and then the activation energy was reduced by 15—25 kJ/mol. At the same oxygen concentration，the increase of heating rate would lead to thermal hysteresis. The numerical simulation study verified that the oxygen-enriched condition could effectively improve the combustion effect of fire flooding. When the oxygen dosage increased from 30% to 50%，the cumulative oil production increased by 11 234 m³. When the oxygen dosage increased from 70% to 100%，the cumulative oil production increased by 3753 m³. It was recommended to use 50%—70% oxygen as the injection gas of oxygen-enriched fire flooding. With the increase of oxygen concentration，the leading edge temperature（350—450 ℃）increased，which improved the stability of combustion and the combustion effect of conventional fire flooding.