Abstract: In order to explore spatial distribution characteristics of diffusion flame, spatially-resolved laser-induced breakdown spectroscopy (LIBS) was used to study the laminar diffusion methane-air flame. The spatial distributions of the threshold energy, the plasma energy and the intensity ratio were obtained at different heights (7mm, 9mm and 11mm) with the flow rate of 0.100L/min and 0.120L/min. The results show that the spatial distribution of flame temperature can be qualitatively described by the plasma energy. Combining the analysis of the plasma energy distribution and the H/O intensity ratio distribution, the positions of the flame front and the width of secondary combustion region can be determined. In addition, according to the relevant measurement, the linear equation for H/O intensity ratio and equivalent ratio can be determined approximately. By this linear equation, the axial distribution of local equivalent ratio and the flame length is obtained. These results have important significance for LIBS application in combustion diagnosis.