Abstract: According to engineering-geological conditions and mining sequences, the limiting equilibrium theory and numerical simulation were used to study the stability of East Open-pit Slope in Daye Iron Mine, China. By analyzing the changes of the stress, displacement field and plastic zones, the stability of the slope was inspected. The results indicate that the safe factor is greater than 1.25, illustrating the slope in a stable state. On three sectional profiles, the distributions and changes of the stress, displacement and plastic zones induced by excavation are ap- proximate. The back filling at the slope bottom not only enhances slope stability, but also provides the safe overlay which is needed in underground mining.