The feature of media changes beneath the Zipingpu reservoir has been studied and the process of permeation with the the water level rise and fall of the reservoir from January 2005 to January 2008 for ambient noise cross correlation by using continuous seismic data recorded by the stations of Zipingpu seismic network and YZP station has been discussed. A moving-window cross-spectrum technique has been used to calculate the seismic velocity changes between station pairs. Results revealed that there is an obvious relationship between seismic velocity and the water level changes with a time delay that may be caused by permeation during three main impoundments and two large scale disemboguements. Impoundment generates a fast and large impact on the superficial layer，and the changes of seismic velocity is the result of increased pressure and permeation during the impoundment. At the first impoundment，the main effect factor is the pressure. Then，during the next two process of impoundment，permeation becomes the main effect factor and has affected the fault in the depth of about 8km.