Abstract: In order to further clarify the influence of pulverized coal particle size on the laser-induced plasma flow characteristics in the process of detecting the composition of pulverized coal by using laser induced breakdown spectroscopy, the screw feeder was used to build coal particle flow detection platform. Spectral datas of 6 kinds of pulverized coal flow plasmas with different particle sizes were analyzed. Under the same experimental conditions, the electron density and temperature of plasma would increase with the decrease of coal particle size. The electron density and temperature of plasma were increased by 19.89% and 13.13% respectively when the sample sizes were < 50μm and 250μm~300μm correspondingly. The results show that, the particle size of pulverized coal has a great influence on the plasma characteristics of laser induced pulverized coal flow. Choosing the appropriate size of pulverized coal can not only improve the spectral intensity but also improve the elements detection limit. It is more favorable for the detection of the low content of elements in the sample.