含油气系统作为油气勘探过程中一种新的研究思路和方法 ,目前正受到越来越多学者的重视。文中依据油气源、油气赋存的层位及储盖组合 ,将鄂尔多斯盆地初步划分为中生界含油气系统、上古生界含气系统和下古生界含气系统。同时 ,重点描述了下古生界含气系统的特征 ,总结了下古生界天然气分布的规律 ,并指出了潜在的有利勘探区带 As a new research idea and method in oil and gas exploration, petroleum-bearing system is receiving more and more scholars’ attention. In this paper, the Ordos Basin is preliminarily divided into Mesozoic petroleum system, Upper Paleozoic gas system and Lower Paleozoic gas system according to the hydrocarbon source, hydrocarbon-bearing strata and reservoir-cap assemblage. At the same time, the characteristics of gas systems in the Lower Paleozoic are described emphatically, the laws of gas distribution in Lower Paleozoic are summarized, and the potential favorable exploration zones