Abstract: The combustion characteristics of soot generated in natural gas diffusion flame (homemade natural gas soot, NGS) were investigated using thermogravimetric analysis under different oxygen concentrations (21%, 15%, 10% and 5%), and compared with those of candle soot, 4 industrial NGS and one anthracite coke. The combustion characteristic parameters of the test samples can be achieved through data analysis. The results show that NGS sample has better ignition features and lower ignition temperature than other NGS samples and the coke with the low volatile matter. Under oxygen concentration of 21% the ignition temperature of homemade NGS is 483.0℃ which is 114℃ and 127.8℃ lower than those of the coke and the candle soot, respectively. The burning index ((dG/dt)max/ti2) of homemade NGS is lower than that of coke due to its high volatile matter. The combustion reactivity of homemade NGS is weak in the late combustion stage. With decreasing oxygen concentration the ignition temperatures of samples change within 50℃. The relative burnout time of homemade NGS is longest, 6.03 min under 21% oxygen concentration, which is 21.3% longer than that of coke. The difference of burnout property between homemade NGS and coke is small. The burnout time of candle soot is also long due to the small particle size of the soot. With decreasing oxygen concentration the burnout times of the samples are prolonged. For homemade NGS the burnout time is 2.97 times longer when oxygen concentration decreases from 21% to 5%.