Abstract: The mining of the bottom coal group of Xinji No.2 coal mine is facing the threat of floor limestone water damage.According to previous production experience,floor limestone water mainly enters the working face through water conducting structures such as faults and hidden collapse columns.Therefore,the primary work of floor limestone water damage prevention and control is to find out the development of coal seam floor water conducting structures.Affected by the huge thick nappe,the three-dimensional seismic exploration technology can not accurately find out the development of water diversion structure under the nappe.In view of this problem,the surface near horizontal directional drilling technology is used to explore the hidden water diversion structure in C¹²₃limestone.The directional drilling is guided to advance in the C¹²₃ limestone of the target layer by means of cuttings logging measurement,drilling time logging measurement,gamma measurement while drilling and wireless measurement while drilling.The development of water diversion structure in C¹²₃ limestone is judged by the changes of drilling mud consumption,water pressure test and hydrological observation.The results show that C¹²₃ limestone have weak water yield and simple hydrogeological conditions.No collapse column and large vertical concealed water conducting(containing) structure are found,and only two small faults are found.The research results not only provide data support for the transformation of mine water control mode,but also provide accurate geological information for subsequent grouting treatment.This exploration method provides a reference for the exploration and treatment of hidden water diversion structure and the transformation of water control mode under similar geological conditions.