On the basis of core analysis，well testing，logging and seismic data and through the r} search on reservoir space and its formation mechanism of various volcanic reservoirs in all the oil fields with volcanic reservoirs，such as the Shengli，Liaohe，Erlian，Dagang，Daqing，Jianghan， Jiangsu，Xinjiang and Bohai oil fields，the basic features，formation conditions reservoir space， reservoir performance，distribution pattern and oil—gas potentialities of volcanic reservoirs are summarized systematically．The evalution and classification criteria of volcanic reservoirs estab— hshed in this paper can be widely applied．Particularly，the author suggests that autoclastic inter一-- mediate basic lavas and lavas with many vesicles and pores are the best reservoirs and that reser— voir space is mainly represented by cracks and crack--pores．And fracture zones，weathering and leaching，and volcanic rock facies have had significant controlling effects on the formation and distribution of volcanic reservoirs．The conclusions and suggestions can play a guiding role in the exploration and development of volcanic oil-gas pools．