Abstract: In order to investigate the coal volumetric swelling during CO2 storage, the self-developed MCQ-ⅡCO2 -ECBM experimental equipment was used to perform coal deformation through injecting CO2 to meager coal,meager lean coal and weakly caking coal samples (100 mm × 100 mm × 200 mm) with constant injection pressure under 31 MPa bulk stress at 25 ℃ . At the same time, the micro-pores were investigated with nine small coal samples (6 mm×6 mm×6 mm) through a micro-CT system. The results show that:At minimum 4. 5 μm observation of CT sec-tion structure,the meager coal porosity (4. 67% ) is less than that of meager lean coal (5. 39% ) and weakly caking coal (12. 10% );During 12 hours of CO2 injection,coal volumetric strain is influenced by pore pressure and CO2 ad-sorption swelling,which is linearly proportional to the amount of gaseousness CO2 storage under 31 MPa confinement pressure;With the same CO2 storage,the volumetric swelling strain of the meager coal is more than that of the weakly caking coal and meager lean coal;Due to the anisotropy of modulus of elasticity,the radial strain increases faster than the axial strain and both of them are linearly proportional to the amount of gaseousness CO2 storage.