Abstract: In order to study the difference of gas adsorption performance between soft and hard coal seams and its influence on gas occurrence, the formation mechanism and structural characteristics of soft coal seam were analyzed. Coal samples from several coal and gas outburst mines in China were collected as test objects, the comparative test of gas adsorption performance parameters of soft and hard coal seams was carried out by using high pressure capacity method, and the difference of gas adsorption performance of soft coal and hard coal were analyzed. On this basis, the relationship between the difference of gas adsorption performance between soft and hard coal seams and the gas occurrence characteristics was studied. The results show that the limit adsorption capacity of soft coal seam is greater than that of hard coal seam; with the increase of gas pressure, the difference of gas content of soft and hard coal seam samples increase gradually, and the change characteristics of the curve are similar to the Langmuir equation, the difference of gas content between soft and hard coal seams is mainly composed of adsorption difference; the difference of gas adsorption performance of soft and hard coal seams not only has a significant impact on the original gas occurrence characteristics of coal seam, but also affects the distribution law of the gas flow field in coal in the process of roadway driving and gas drainage, it is necessary to work out effective gas extraction technical scheme according to the combination characteristics of soft and hard coal seams.