Abstract: The analyzing of sediment index is the key technology to research the distribution of sand as to explore the oil-rich area,which is fairly meaningful to the oil exploration.This research area locates in the Wuqi county in the Ordos basin.To start with the analyzing of the well survey materials,according to the observation and description of the core,and with studying of the reginal geological materials,we give a definition and demarcation of the sedimentindex in this area.We define thatitis manly river sedimentin Jurassic,towards the Yan-9,it gradually turned into river and lake delta sediment.We also distinguished the sub-facies and micro-facies.