Abstract: The characteristics of Carboniferous and Permian,Triassic,Early-Middle Jurassic coal measures in Ordos Basin and their hydrocarbon potential are investigated on their petrology,property,coal pyrogenation.The study results indicated that the liquid hydrocarbon generation rate of coal-measures source rock is low,but the gas hydrocarbon productivity is larger;the hydrocarbon potential of Carboniferous and Triassic coal are better than that of Jurassic coal.Based on analysis of coal generation conditions,coal petrologic and quality properties and pyrolysis measurement results,the hydrocarbon precursor type of Ordos Basin is type Ⅲ and can be divided into three grades:Triassic,Permian(on eastern boundary) semi-bright coal and vitrain belong to Ⅲ₁,the Carboniferous(on eastern and western boundaries) semi-dull coal belongs to type Ⅲ₂,Permian(on western boundary),Jurassic durain and dull coal belong to type Ⅲ₃.