Abstract: The microscopic characteristics of solid particles have important influence on the formation of fluid slag, coarse slag and fine slag during entrained-flow gasification process. Based on the bench-scale opposed multi-burner (OMB) gasifier, solid particles were sampled at different axial distances along the gasifier chamber under typical operating conditions (oxygen and carbon atomic ratio at 1.0). The microscopic characteristics of solid particles were studied by using N₂ adsorption-desorption and scanning electron microscopy (SEM) methods. The results show that the solid particles are comprised mainly of porous irregular particle and spherical particle, and few solid particles generated at burner plane perform as dense irregular and hollow shape. As the gasification reaction proceeds along the axis of gasifier, the surface structure of particles becomes rougher, and the pore structure increases. The isotherms of particle samples are all type Ⅱ, and the particle samples consist of continuous and complete system of pores. The hysteresis loops are H3-type, and there are a large amount of fractured pores. BET surface area and pore volume increase with increasing distance from the burner plane, and average pore diameter gradually reduces, and larger changes occur in the vicinity of the burner plane. The mesopores less than 10 nm vary apparently and increase with increasing distances from the burner plane, while the pores larger than 10 nm are almost unchanged.