The Tarim basin, located in northwest China, is one of the largest basins in the world that has not been well explored. In recent years the large scale of petroleum exploration in the basin has led to the discovery of a series of oil and gas fields with an approximate 1:1 ratio of oil to gas resource. This means that the natural gas resource is very important for the hydrocarbon resource in the Tarim basin. In this basin most of the discovered gases are condensate-associated gas and oil-associated gas. Research on chemical components and isotope composition of carbon and hydrogen of natural gases from the Tarim basin shows that all discovered gases in this basin are thermogenic. With respect to source organic matter, there are two types of gases: (1) oil-type gas generated from Sinian to lower Paleozoic marine source rocks with the sapropelic organic matter, with -44.5 to -33.8 parts per thousand of delta(13)C(1), -42.0 to -28.1 parts per thousand of delta(13)C(2), -35.4 to -28.4 parts per thousand of delta(13)C(3), and heavier than -200 parts per thousand of delta D-1 and (2) coal-type gas generated from Mesozoic terrestrial source rocks with the humic organic matter, with -40.5 to -33.1 parts per thousand of delta(13)C(1), -29.7 to -21.3 parts per thousand of delta(13)C(2), -26.3 to -20.3 parts per thousand of delta(13)C(3), and lighter than -200 parts per thousand of delta D-1. Based on the geochemical characters and geological setting, Tabei uplift region is regarded to have some reservoired gas pools formed by mixed mature oil-type gas with post-mature oil-type gas. Some reservoired gas pools are formed by mixed mature oil-type gas with mature coal-type gas.