Abstract: In this paper, the influence of oxygen concentration on the physical and chemical properties of soot particles in n-heptane/toluene flame was studied by building a coaxial laminar diffusion combustion test bench, and the graphitization degree and oxidation reaction activity of soot particles were analyzed by using Raman spectrometer（Raman） and thermogravimetric analyzer（TGA）.The results show that in laminar anti-diffusion flame, the increase of oxygen concentration can accelerate the growth process of soot particles, increase the degree of graphitization and reduce the reactivity; At the same oxygen concentration, blending 10% polymethoxydimethyl ether in n-heptane/toluene can reduce the graphitization degree of soot particles and increase the reaction activity.