Abstract: Fuxian County is an area where the degree of exploration for oil and gas in Yanchang Group in the southeast of Erdos Basin is relatively low.Reservoir is a key problem that limit the petroleum exploration in Yanchang Group in this area.Based on the researches of predecessors,the depositional genesis and distribution of reservoir sands as well as the petrologic characteristics,the pore texture and the physical properties of the main Yanchang Group oil reservoirs were studied by using the data of outcrop,core and logging.The result shows that Yanchang Group in this area is a typical tight reservoir with extra-low porosity and permeability.Chang 2,Chang 6 and Chang 8 are three favourable oil-bearing horizons developing in Yanchang Group in this area.