Abstract: This paper focuses on the study of petrographic characteristics of Jurassic inertinite-rich coal and the Paleo-environment during the coal-forming period in southern margin of Ordos Basin. 27 coal samples were collected from the No. 4 coal seam in Hujiahe Coal Mine of Binchang Coalfield and were analyzed using Coal Petrology Theory and statistical analysis. The results showed that the coal sample of No. 4 coal seam in Hujiahe Mine was a composite of inertinite(66.97%), low vitrinite(30.00%), and liptinite(2.60%). The GI-TPI, GWI-VI and three phases diagrams were developed from the petrological properties ,and we deduced the Paleo geographic environment of No.4 coal seam in Hujiahe Coal Mine. It was concluded that the coal forming environment was dry and oxidized, the hydrodynamic conditions of peat mire were weak, the coal facies was in dry forest peat swamp, and the coal-forming plants were mainly woody plants.