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With the rapid development of computer technology, numerical simulation analysis has been widely used in geotechnical and underground engineering research and design, the cost of lower than the physical model, and can calculate and analyze quantitatively the process of stope mining of rock stress magnitude, displacement variation and development of plastic zone, determine their dynamic changes of each step recovery process, and thus the stability of surrounding rock state judgment. Numerical simulation of initial stress field is consistent with the actual stress field, numerical simulation is to determine the success of underground engineering fundamentals. Although the stress field measurement is to provide information on the most direct way, but each measuring point measurement results reflect only the local stress field characteristics measuring point, however, the project site due to space and funding and other reasons, it is impossible for a large area measured. In this paper, Wu Zhuang iron ore as the research object, complete the main work includes: 1, on the surrounding rock failure mechanism and failure criterion are described, and the current commonly used rock strength criteria, the amount of displacement tolerance limits and whether the plastic zone interconnected three kinds of criteria are analyzed. Because the influence of surrounding rock stability of many factors, relations are complicated, this paper uses three kinds of surrounding rock stability criterion for a comprehensive judgment. 2, according to the project area to stress the limited observations, combined with topography data, using the stress boundary method, the initial stress field of the fitting. Stress boundary law FLAC 3d simulation geotechnical initial stress field provides a new way of thinking, that the initial stress field in the formation process, the calculation model with no velocity boundary condition, only the surface of the model Base observation applied stress and the stress boundary conditions are kept constant. 3, in the initial stress field calculation process, the analysis of the elastic step inadequacies solving method, this paper proposes a two-step phased elastoplastic solution method to generate the initial stress field. This method stresses the initialization process has great flexibility, and the resulting initial stress field is also more in line with the actual site. 4, through the numerical simulation of the inverted initial stress field for 30 different programs stope structure parameters of a large number of numerical simulations, and the recovery process of surrounding rock stress, displacement and plastic zone variation distribution carried out a detailed analysis and comparison. 5, according to the above results, plotted with the entry panels stope span tensile stress between the stope length Xiang plate curves between tensile stress and their effects on items slate combined effect of the surface tensile stress. The results showed that: the stope span stope roof strata on the stability of the stope is far greater than the length. Stope roof exposed area size is not determined the stability of stope roof strata only factor, the shape of the roof exposed surface stability roof strata great impact. Exposed surface using a long strip of roof shapes, can improve stope mining production capacity and ensure safety. Therefore, for the steep Heavy orebody proposed a \
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