In Ordos Basin, coal-bearing strata of Carboniferous-Permian are the main layer for coalbed methane, shale gas and tight sand gas stacked accumulation. Three kinds of gas reservoirs belong to thermal genetic gas reservoir, but their reservoir characteristics are different. On the basis of a large number of drilling and logging data, the plane distribution characteristics were discussed that of three kinds of gas reservoirs, Taiyuan Formation and low of Shanxi Formation of U-1 well was selected, which is representative, as the destination layer. The data of geochemistry, reservoir properties, gas content and gas isotope from vertical were analyzed. The results show that shale and coal seam have high organic content ,which is mainly for type Ⅲ kerogen and in high mature and over mature stage. The total quantity of hydrocarbon in organic matter is 154 mg/g. In terms of porosity, tight sandstone reservoir is higher than coal reservoir and shale reservoir, and shale reservoir is lowest. The reservoir porosity is mainly composed of nano pores, which have irregular structure and are open. Tight sandstone in permeability is better than coal seam and shale, and shale is poor. In terms of gas bearing, coal reservoir is higher than tight sandstone reservoir and shale reservoir, and shale reservoir is lowest. In the study area Taiyuan Formation to the low of Shanxi Formation mainly formed the composite gas reservoirs of coalbed methane, shale gas and tight sandstone gas.