Abstract: Geological structrue, structural plane, rock property, cave shape and groundwater are important factors in qualitative evaluation of stability for caved foundation.Based on elastic theory,the stress distribution around cave has been deduced in the caved rock foundation. The stability of rock foundation can be calculated and analysed by the Griffth failure theory.The size of foundation base, the thickness of cave roof,the diameter and shape of cave have great influence on foundation stability. The ’vacuum suction’ produced by groundwater has little influence on foundation stability. The effect on foundation stability is small when the cave is filled with some materials.