Abstract: In order to deeply explore mechanism of the physical and mechanical properties of coal in the development of coal and gas outburst, in connection with the current state of insufficient research in characteristics of grain size distribution and grain grading of outburst coal, based on the screening data of typical outburst coal, grain size accumulation curves of outburst coal are drawn, the characteristic particle size and gradation parameters of outburst coal were determined. The particle size characteristics and gradation characteristics of outburst coal were analyzed. The types of outburst coal were classified. The variation law of coal particle size before and after outburst was discussed. The research results show that the distribution range of the characteristic particle sizes and gradation parameters of typical outburst coals is relatively large, with the maximum and minimum values differ by 1 to 2 orders of magnitude; there are obvious differences in the characteristic particle sizes and gradation parameters among different outburst coals; the gradation of outburst coal is mainly characterized by poor gradation; drawing on the engineering classification standards of soil (five types: well-graded gravel, poorly graded gravel, poorly graded sand, clayey gravel or silty gravel, and fine-grained soil containing coarse grains), poorly graded gravel is the main type of outburst coal; the particle size distribution characteristics and gradation characteristics of the coal after outburst can represent those of the coal before outburst. Before conducting the outburst simulation test, it is necessary to carry out the analysis and research on the particle size distribution characteristics and gradation characteristics of the simulated outburst coal. Laboratory simulated outburst coal samples should be prepared based on the characteristic particle size and gradation characteristics of the outburst coal under actual conditions to ensure the consistency of the physical and mechanical properties between the simulated outburst coal samples and the actual outburst coal underground. The analysis conclusion can provide parameter basis for the preparation of coal samples in the laboratory to carry out outburst simulation experiments.