Abstract: The exploration practice in the Beijing-Tianjin area shows that the key point of improving seismic interpretation level in a complex district lies in the high accuracy of seismic work,extraction of available seismic information and the use of the comprehensive interpretation method basing on bo th structure interpretation and seismic stratigraphy.This paper presents the geological interpretation results of analysing the Third member of Shahejie Formation in Beijing-Tianjin Depression by using the method stated above.It describes the seismic facies,sedimentary facies as well as the generation,accumulation and distribution of hydrocarbons,and points out that the lower part of the member is a subaqueous fan and point bar deposit,while the middle part is a fan-delta deposit.According to the thermo-evolution-profile and TTI estimated,it is assumed that the lower part of the member is source rocks with sandstone development and is also a very good reservoir rocks because of having two sets of source rock reservoir and seal rock.Having structures such as Jiuzhou anticline and its down dip and Liuquan fault structure,it is favourable for hydrocarbon accumulation.