Abstract: In the Ordos Basin, the major controlling factor for the Early Palaeozoic gas exploration is whether (effective) source rocks are developed. The authors contend, on the basis of sedimentary-tectonic evolution, sedimentary environments, and hydrocarbon-generating potential of the Early Palaeozoic strata as well as the (coupling) relations of sandstone distribution and central gas field, downward migraton of the Upper Palaeozoic gas and geochemical signatures, that the gas sources of the central gas field are derived from the Upper Palaeozoic coal measures and marine source rocks in the Benxi and Taiyuan Formations.