Abstract: The aim of this paper is to quantitatively evaluate the effect of mining-induced damage on the stability of joint rock slope. By means of site survey and fuzzy C-mean optimization algorithm,the random distribution parameters of the dip direction,dip angle,trace length and density of two dominant joint sets in footwall migmatite slope of Dagus- han iron mine were obtained. Considering the relationships among Hoek-Brown parameters ( m, s) and Geological Strength Index ( GSI) and disturbance coefficient ( D), the random distribution parameters of jointed rock mass strength were obtained by Monte Carlo method. After establishing the relationship between the damage and disturbance parameters of jointed rock mass,the Kawarnoto damage tensor was employed to carry out the numerical simulation of the mining-induced damage. Then the random distribution parameters (D) and rock mass strength with spatial-tempo- ral distribution characteristics and anisotropy were obtained according to the Rosenblueth principle. The slope reliabili- ty index was calculated based on the strength parameters of rock mass with spatial-temporal distribution characteris- tics. The result shows that while the elevation of the stope bottom decreases from -87 m to -450 m,the reliability in- dex of slip circle from the top of slope to -87 m level decreases 7. 7% relatively. This is because that the increase of mining depth aggravates the damage in joined rock mass and weakens its strength. The potential slip surface gradually move to the slope surface,which has a greater correlation with the damage in rock masses near the slope.