Xiaocaohu area is rich in hydrocarbon resources with low degree of exploration and high potential . With the exploration increasing, structural reservoirs become rare, while the difficulty of the stratigraphic-lithologic reservoirs increase. According to the research on the accumulation conditions of the natural gas in Xiaocaohu area, Taibei Sag, the accumulation mode was discussed. The result showed that the reservoirs are cont rolled by structure, lithology and fault, among which lithology and fault are the key factors controlling the accumulation. On the basis of the exploration of lithologic reservoirs in two nose-shaped uplifts and sag, extending periphery block was carried out to develop fine gas reservoir description. The drilling of lower channel sand bodies along the ridge of the nose-shaped uplift is successful, making Ge 7 to Hongtai 2 a continuous oil/ gasbearing area.