Abstract: Using the scanning electron microscope,the microstructure of coal is studied in the range of micron,as fracture,breccia,cataclast,mylonite and slip plane.These microstructures have the direct influence on the coal reservoir property.The fracture and bereccia increase medium-large pores and effective porosity of coal;cataclast and mylonite increase specific surface and methane absorbability,at the same time,filling pore and plugging channel too.The microscopic evidences could be provided for studying the generation,storage,migration of coal bed methane theoretically,and should be an index for evaluating and extracting coal bed methane practically.