Abstract: Haofanggou backbone dam is built on the surface of working face 9-208 of Dianping Coal Mine. In order to realize safe mining under the dam, according to the actual geological mining conditions and relevant data above and below the mine of Dianping Coal mine, the overburden fracture height theory and probability integral method are applied to conduct safety demonstration on the feasibility of mining working face under the dam, and then the theoretical analysis results are verified by numerical simulation. The final comprehensive analysis, evaluation and demonstration show that the mining of 9-208 working face will not cause damage to the dam body, and the technical measures adopted provide reliable technical support for safe coal mining under the backbone dam.