Abstract: The slope of Dading open-pit iron mine in south China has the characteristic of low rock strength and bad stability. Its basic information on engineering-geological conditions, hydro-geological conditions and rock mass structures together with physical and mechanical properties of rock mass was derived from systematical field and laboratory investigations, experiments and tests. Stability analysis and optimum design were done for the slope by using a combined method of numerical modeling and limit equilibrium analysis. The slope angle increases more than 3° compared with the original design.