In order to evaluate the seismic activity and crustal stability in the Three-Gorge hydropo-wer project area on Changjiang River, some new isotopic dating methods were used in determination of the ages of fault activity in and around the dam area. Analysis of the obtained data indicates that the age of the latest activity of the major faults around the project site is (145-20)?104a and two age data of the latest activity of the major faults in the dam area are 220?104a (as they had not been activated in the Quaternary time) and (131-54)?104a. As studied by the author, the lower limit of the age of latest fault activity in eastern China affecting on the stability of the project is identified to be 5?104a, that is, the fault with its age equal or less than the identified age data may be activated (creep or earthquake) in the period of operation of the project. Thus the faults in the Three-Gorge dam area do not belong to the engineering-active faults.Comprehensive analysis of the age data of latest fault activity, historic seismic and micro-seismic data indicates that no recently active faults exist in the area with diameter of 15 km around the projected Sandouping Dam site. Therefore, the crustal stability conditions in the dam area are good. Comprehensive analysis of fault activity, seismic parameters and crustal structure indicates that the crustal stability in the dam area is classified as a stable area. From viewpoint of the crustal stability the projected Sandouping Dam site is suitable for construction of a large dam.