In this paper the ground stresses are calculated near Daliushu dam-site in Heishan gorge of Yellow River by extracting the boundary condition using sub-model of the region tectonic stress simulation and the rupture risk is estimated in the area.The results show that the major principal ground stress is mainly horizontal and controlled by the faults. In the plane model

the faults and the soft rock can cushion and digest the stress and in the cross-sectional model

and the stresses are always concentrated in the joint and inflection point of faults.The color contour map of rock rupture risk coefficient KR shows that the risky rock rupture area is mainly around the faults and especially around the fault F201 in deeper crust.The color contour map of fault gliding risk coefficient KF shows that in plane model fault F201 and parts of other faults are in critical status of gliding and in profile model the critical area is mainly in fault F201 within depth of 12-17 km

which indicates that earthquake may occur along the fault F201 followed by ruptures of other faults near the joint.Therefore

the activity of fault F201 is the key to the tectonic stability of dam-site and if earthquake occurred along fault F201 the ground surface will rupture for at least 5 km in the south plate in view of the epicenter which would damage the dam.