The traditional petroleum theory is helpful to search oil in sedimentary rocks. However, as oil-gas exploration has been intensively concentrated on sedimentary regions, the oil-bearing sedimentary regions become less and less. To look for oil in non-sedimentary areas caught more and more attention. This paper analyzes the oil-gas potential in the volcanic rocks worldwide, and studies the oil-gas reservoir formation conditions of volcanic rocks in basins. The volcanic-hosted oil-gas reservoir is normally located at the lower sequences, where with a low exploration but high potential shall be a new vital oil-gas exploration area. Some volcanic basins in circumPacific, Mediterranean sea and middle Asia are of good oil-gas reservoir-forming conditions, where can become the major areas for volcanic-hosted oil-gas.