Abstract: In order to ensure the safe mining of Zhongjiu Iron Mine,according to the hydrogeological engineering geological conditions and mining methods of Zhongjiu Iron Mine,the height of waterconducting fracture zones,the reasonable thickness of waterproof pillars and its location are analyzedand calculated by theoretical analysis and numerical simulation.Moreover,combining the hydrogeological characteristics and development depthof Quaternary aquifer in Zhongjiu Iron Mine ,the disturbance boundary of overburden in waterrich orebody mining in ZhongjiuIron Mine is calculated.

Key words: Under Three′ mining, Height of waterconducting fracture zone, Thickness of waterproof pillars, Top mining boundary