In order to assure the balance of production and the transition from open-pit mining to underground mining without stopping production,the open pit and underground mining were carried out simultaneously in the vertical direction at Shirengou Iron Mine.The mining for nine kinds of stope structure parameters were simulated using 3D-finite-element numerical simulation method of ANSYS.At the same time,a comprehensive fuzzy evaluation model was established,in which safety and economic benefit was took into account.And such optimized stope structure parameters as 50 m room length,5 m cap pillar,10 m interstall pillar and 12 m floor pillar were determined.The result of a level mining indicated that the stability of stopes were very good.