Abstract: The reservoir property is the important factor for gas accumulation in the volcanic gas field of the Xujiaweizi fault depression. The core, debris and microscope structures of the volcanic rocks were observed, and the features of reservoir spaces were analyzed. The results show that the reservoir spaces contain three kinds of primary pores, secondary pores and facture-pores developed in the different places. The development of the reservoir spaces are dominated by lithology and lithofacies. The reservoirs in the air hole rhyolite of the upper lava subfacies, flood tuff in the heat clastic fluid explosive subfacies, breccia sandstone in the lava neck volcanic conduit subfacies are well developed. The primary pores are short of connectivity, which was improved by the diagenetic and paulopost fractures. The pores of the volcanic rocks became the primary gas pores, condensed shrinkage joint, devitrification emposieu, arkosic dissolved pores and volcanic ash-dissolved pores under the actions of magma condensation, weathering and leaching, organic acid and carbonate corrosion. The coupling action of the fractures with the displacement and groundwater injection impacted the denudation of the volcanic reservoirs.