Abstract: Secondary stress after excavation could result in deformation of the surrounding rock at Jinping hydropower plant because of deep embedment of the aqueduct tunnel and low compression strength of rock.Therefore,it is an important to appropriately evaluate stability of the deformed surrounding rock.This paper presents a numerical model for evaluating stress state and stability of the deformed surrounding rock under an embedment at a great depth.Two methods: one related to strain ratio and the other related to compression strength,were used to determine locations of deformed surrounding rock and overall stability of the surrounding rock.