Abstract: Heishan open pit mine has turned into underground mine. The hanging-wall ore in western reinforced slope is a large size ore body，which would be mine by pillarless sublevel caving method. The process would disturb the stability of the rock mass. Studies should be made on the behavior of slope deformation and the formation of overburden cover. Based on the data from tests of 3D contact-free measuring system and point load instrument system upon the complex slope conditions in western area of Heishan open-pit mine，the generalized Hoek-Brown criterion is applied to estimate the deformation and strength parameters of jointed rock masses. Then the behavior of rock mass and instability of the slope is analyzed using RFPA，and it has important instructive meaning.

Key words: Hanging-wall ore, Shape Metrix 3D, Slope instability, RFPA, Numerical simulation