Abstract: Gezhouba Water Control Project is the first dam on the Yangtze River., which is the important part of the Three Gorges Project.week intercalation is the most impotant reason that lead to shut down the energine construction which was started in less than two yeaes. At the same time, it was the key problem of anti-erosion and anti-sliding stability of dam foundation. The Gezhouba Water Control Project has beening running for nearly 30 years, and insiders general concern about whether the properties of these weak intercalation(shear zone) may deteriorate under the long-term seepage pressure, which may reduce the value of mechanical parameters and then endanger the dam safety. This paper makes a conclusion that the weak intercalation(shear zone) stay stability basically and has no signs of deterioration by focusing on the two geological monitoring points of foundation gallery and through analyzing of geological observation and the result of sampling test, which thanks to the environment condition that the weak intercalation(shear zone) is stability and benefit from the previous investigation. The research result can be used for reference in similar problems.