Abstract: Abstract：Based on a study of gas components and carbon isotopes and an integrated research on the actual geological conditions, the authors investigated the genetic types and causes of natural gas distribution，and divided the gas source contribution and source characteristics in detail into different segments. The results show that in the study area there are three types of sources and origins of natural gas, i.e., self-storage type gas derived from Xujiahe coal serial hydrocarbon rocks, mixed type gas mainly derived from coal source rocks, and gas mainly derived from deep source. It seems that the gas mainly comes from deep-seated sources.