Abstract:The fractal feature of geological structure and the relation between fractal dimension of structure and danger extent of gas outburst are analyzed in three scales of coal field,mining area and stope,respectively. It is shown that geological structures are of fractal features,and there is a positive correlation between fractal dimension of structure and danger extent of gas outburst over the three scales. The results indicate that multi-scale assessment of outburst tendency of coal and gas can be made based on fractal measurements independently or supplemented by other assessing methods.