Volcanic craters are favorable targets in gas exploration an d developm ent, because surrounding these craters there exists the superimposition of various types and facies of volcanic rocks which are characterized by relatively remarkable reservoir thickness, large reservoir porosity and fairly good reservoir properties. The determination of volcanic craters is hence very important in gas exploration and development. Using thin section X-ray diffraction techniques, hi s paper identified arfvedsonite in volcanic rocks from Songliao Basin，and thus confirmed that the volcanic rocks are composed of pantellerite. As the late evolutionary stage product of alkali-rich magma, pantellerite is always accumulated near the volcanic crater due to its high viscosity and poor mobility. As pantellerite can be used as important evidence for the existence of crater, it has an important significance in improving the efficiency of gas exploration and development in volcanic rock areas