Abstract: Aiming at characteristics of coal sediment basement and water controlled by tectonic，on the basis of the work of Ordovician limestone hydrogeology additional exploration and special research in mines，shortage and key technical difficulties in floor water prevention theory and technology were concluded including geological factor of coal sediment basement，tectonic water-controlled mechanism，elaboration exploration degree of water-induced tectonic，effective water-resisting layer height distribution rule，etc．By comprehensively considering theoretical research and technical application status of water prevention，initial solution and technical measure of floor water prevention in lower-group coalseam mining were present which had important significance and practicable value for floor water prevention of lower-group coalseam mining in Zhuozishan coalfield