Abstract: In order to analyze the correlation of ash content, volatile matter and porosity of coal and the effect of the pore characteristics and coal hardness coefficient on the initial speed of methane diffusion, 84 coal samples were taken from 8 typical mining areas in our country, and the corresponding tests were carried out. It was found from the numerical analysis of the experimental data that the fitting function of the ash content, volatile matter and the porosity of coal samples in most mining areas obeyed the binary linear function, and only the fitting function of the coal sample in Jincheng Mining Area was a curved surface function; the mathematical relationship between the porosity, hardness coefficient and initial speed of methane diffusion of coal samples in every mining area was obvious, it can concretely divided into three kinds. Based on the corelation between the ash content, volatile content and porosity of coal samples and by taking the impact of the hardness coefficient of coal into consideration, the more accurate fitting function was obtained, the change tendency of the calculated value and the measured value was basically the same, which can provide some reference for analyzing the characteristics of coal and gas outburst disasters, in addition, it has important practical significance for studying the new index of coal and gas outburst prediction.