Abstract: The use of mining subsidence land for construction land development has been widely used in the planning and development of mining cities in China. With the increase of building layers and loads,the foundation type of buildings has gradually changed from shallow foundation to deep foundation. Reinforced concrete bored pile is a form of deep foundation. The theory and practice of anti deformation design of shallow foundation in mining area are relatively mature, but the research 0 n anti deformation design of deep foundation is relatively insufficient. In order to solve the reinforcement design problem of the reinforced concrete bored pile in the min ing area under the horizontal deformation of the foundation soil,the stress ,deformation and working characteristics of the pile body under the normal horizontal load and the horizontal deformation of the foundation soil are analyzed,and the deflection differential equation of the flexible pile under the horizontal force is derived. By substitu ting the displacement value of the foundation soil into the displacement solution of the deflection differential equation,the displacement of the foundation soil is transfor med into the equivalent horizontal concentrated force of the pile top,and then it is superposed with the conventional horizontal force as the load effect of the pile top un der the influence of mining. When determining the effect of the horizontal force on the pile top,the total horizontal force and bending moment at the bottom of the pile ca p transfer the horizontal force to the top of the pile according to the way of average distribution. The maximum bending moment of the pile body is calculated according to the flexural member,and the maximum shear force of the pile body is calculated according to the shear member. The analysis of the calculation results of the reinforc ement of the foundation pile under the horizontal deformation value of the foundation soil given by the calculation example shows that the diameter of the longitudinal re inforcement of the foundation pile increases from 16 mm to 18 mm,the reinforcement amount increases by about 26%,the diameter of the stirrup increases from 8 mm t 010 mm,and the reinforcement amount increases by about 56%. By increasing the amount of longitudinal reinforcement and stirrup reinforcement,the anti deformation ability of pile can be improved. At the same time,the sliding layer at the bottom of the bearing platform can effectively reduce the friction transmitted by the foundation s oil to the bearing platform and the upper structure,reduce the additional stress of the bearing platform and the upper structure, and indirectly improve the overall deform ation resistance of the building. t o deformation resistance of the building.