Abstract: In order to reveal the differences in microcrystalline structure parameters and pore structure between gas outburst coal and raw coal, this paper studied the structural parameters and fractal characteristics of coal samples inside and outside outburst holes in Sanjia Coal Mine based on XRD, low-temperature liquid nitrogen adsorption, mercury injection and other experimental methods combined with fractal dimension theory. The results show that the side chain content, aromatic hydrogen rate and aromatic carbon rate of gas outburst coal are higher than those of raw coal; outburst coal has better hydrocarbon potential; the outburst coal I₁ and I₂ are larger than the raw coal, indicating that the aliphatic functional groups of the gas outburst coal are higher than the aromatic structural functional groups; due to the change of the dense ring structure in coal, the number of effective stacking aromatic slices of gas outburst coal is lower than that of raw coal; the coalification index increased slightly, indicating that the content of side chain in raw coal was lower than that in gas outburst coal, resulting in an increase in the number of relative aromatic rings. According to the mercury injection data, the comprehensive geometric fractal dimension of the raw coal is 3.30, and the gas outburst coal is 3.37. The fractal dimensions of micropore surface area of gas outburst coal and raw coal are 2.62 and 2.13 respectively, and the fractal dimensions of micropore surface area are 2.45 and 2.23 respectively.