As the simplest conversion route, combustion is extensively applied to oil shale utilization. To improve oil shale conversion techniques, we used non-isothermal thermogravimetric analysis to explore the combustion reactivity and kinetics of Huadian oil shale at various oxygen concentrations (10, 20, 30, 50, 65, and 80 vol %) and heating rates (5, 10, and 20 degrees C min(-1)). With an increase in oxygen concentration, the combustion performances of oil shale could be significantly improved; the volatile releasing temperature, ignition temperature, and burnout temperature decreased; the mass loss rate increased; and the integrated combustion characteristics of oil shale were enhanced. These improvements were attenuated when the oxygen concentration exceeded 50 vol %. When the oxygen concentration increased from 10 to 80 vol %, the average activation energy in the second combustion stage increased from 46.85 to 117.98 kJ mol(-1) by the Kissinger-Akahira-Sunose method, from 46.85 to 117.98 kJ mol(-1) by the Starink Method, from 59.08 to 129.17 kJ mol(-1) by the Friedman method, and from 36.34 to 57.58 kJ mol(-1) by the Coats-Redfern method at a heating rate of 20 degrees C min(-1). Results indicated oxygen enrichments beyond which additional enrichment yields significantly less enhancement to the combustion process.