Abstract: Based on the principle of surface chemistry, author pointed out the method of calculating coal surface energy with absorption parameters, and the surface energy of coals is the most important reason in absorb difference of coals, which is related to absorbed content, absorption constant, the properities of absorbed gas and coals. The theory of coal surface energy can be applied to the researches, such as coal outburstion, migration of coal-generated gas and oil and methane drainage,etc.The medel of three-layers structure of coal absorption was introduced.