Hutubi and Huoerguosi oil and gas field is located in the southern margin of the Zhungeer basin. As an important oil gas area of Western China they have been the source of attention for many scholars widely. Now, there have been breakthroughs in the exploration theory. However in the genesis, the source sentence still exists as the consciousness is disputed. This paper, through the analysis of the components of light hydrocarbon characteristics in the natural gas, digs into the analysis problem arising from a large number of basic data statistics and experiments (including isotopic characteristics of benzene, toluene, cyclohexane, n-heptane, methyl cyclohexane, 2-methyl cyclopentane, and pentane),and discusses the origins of the natural gas and source of Hutubi and Huoerguosi oil and gas field. The natural gas from Hutubi and Huoerguosi oil and gas fields has the same source, i.e. type III as a precursor of hydrocarbons, which is a typical coal type gas and comes from the coal-measure hydrocarbon source rocks from the Jurassic times.