For the purpose of accurately forecasting development of favorable volcanic reservoirs in Chepaizi area，Junggar Basin，the pores/fractures characteristics of different lithologies of volcanic rock were observed with microscope and Computer Tomography（CT）. And then effects of secondary action on volcanic rock evolution were discussed combining with geological conditions. Moreover，the relationship between oil-bearing and reservoir characteristics of volcanic reservoir were ascertained with core analysis，log data interpretation and fluorescence slice observation. The results show that in the study area，the lithologies and lithofacies of volcanic rock control the development of primary pores/fractures of volcanic rocks，and they also affect the formation and development of secondary pore/fractures. Vesicles，contraction fractures，volcanic glasses are commonly found in rocks of andesite and andesitic breccias，which can provide initial reservoir spaces for the extension of fracture under tectonic stresses and for the infiltration，dissolution and precipitation of surface and underground water. As for the tuff，its particles were altered seriously due to the hydrolysis-dissolution of unstable minerals and the majorities of primary pores were refilled due to strong mechanical compaction underground，so the volume of reservoir space was reduced dramatically and its property became poor. Almost all of the oil-bearing volcanic rocks in the study area are relative to factures，and the oil-filling pores are only found near fractures. According to this，the pore porosity，the fracture porosity，and the fracture factors of volcanic rocks were calculated using log data，therefore the favorite reservoir areas of volcanic rocks in the study area were forecasted，which include the south area near Well Pai 674，the east area near Well Pai 66，and the northwest area near Well Pai 682.