Abstract: The volcanic rock of Yingcheng Formation in the Changling Faulted-Depression of the Songliao Basin is thick with various types and facies.Microscopic characteristics and formation mechanism of volcanic rock reservoirs have been systematically observed.Formation of volcanic rock reservoirs is divided into 2 stages,the initial diagenesis stage and the later diagenesis stage.During the initial diagenesis stage,primary pores are formed.And in the later diagenesis stage,secondary pores are formed.Tectonic effects take place through out both the 2 stages,forming various primary and secondary cracks.Deep hydrothermal flow and hydrocarbon-generating effects have obviously transformed reservoir.Many large-scale tectonic movements are the main reasons that volcanic rocks turn to high quality reservoirs.Substantially developed high quality volcanic reservoirs in deep formation have enormous exploration potential.