The evolution of morphology of the soot particles formed in methane/air flame was investigated by atomic force microscopy.The soot particles at different height above the burner(HAB)were obtained by thermophoretic sam-pling technique.The morphology of thosesoot particles reflected the processes of soot formation including nucleation,coalescence,surface growth,agglomeration and oxidation.With the increase ofHAB from 30,mm to 45,mm,the averaged equivalent volume diameterof single soot particles gradually increases from 8.72 nm to 11.36 nm.Then,averaged equivalent volume diameter decreases to 9.41 nm in the subsequent combustion.Single soot particles spread out on the mica substrate and possess a low sphericity ratiowithin the range of 0.01—0.30, indicating that those soot particles are liquid-like and far from being fully carbonized.Sphericity ratio increases with the increase of equivalent volume diameter,especially at higherHAB,which suggeststhat particle carbonization degree is related to particle size and the height above burner.%采用热泳取样技术获取了甲烷/空气扩散火焰中不同高度的碳烟颗粒，并通过原子力显微镜研究了碳烟颗粒的三维形貌随火焰高度变化的演变规律．研究所选高度下碳烟微粒的三维形貌反映出了碳烟微粒在扩散火焰中形成的各个过程，即成核、表面生长、团聚和氧化．当火焰高度 HAB从30,mm 增加到45,mm 时，单碳烟粒子平均粒径从8.72,nm 增加到11.36,nm；当 HAB＞45,nm 时，单碳烟粒子平均粒径逐渐降低；单碳烟粒子的球度比主要分布在0.01～0.30之间，表明这些碳烟粒子的碳化程度较低，呈类液态；球度比随着颗粒体积当量直径的增加而增加，且随着HAB的增加球度比随体积当量直径的增加速率变快，说明单碳烟粒子碳化程度与颗粒大小和火焰高度相关．
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