In the present paper, under optimum experimental condition, two middle-low alloy slab and homogeneous samples were analyzed under the condition of spatial resolution about 100 μm by scanning mode. Element 2D intensity distribution can be converted into 2D concentration distribution via establishing calibration curve. The results showed that there is a central segregation for C, Si, Mn, P, S and Cu for 86# slab sample, and C, Si, P and Ti for 174# slab sample, the width of segregation band was estimated, and it agrees well with metallographic analysis. Homogeneous sample was analyzed by scanning mode, the result showed that C, Si, Mn, P, S and so on are well distributed, and there is no segregation band existing. 2D distribution of element intensity or concentration can be used to indirectly reflect sample’s homogeneity. Compared with traditional metallographic analysis, LIBS can not only show central segregation bands position and width, but also provide 2D concentration distribution for C, Si, Mn, P, S etc in detail. This method can be used to characterize segregation band position and its width rapidly, and provide theoretical guidance for improving metallurgical process.