The grassland areas in eastern Inner Mongolia and northern Xinjiang are rich in coal and groundwater resources. The mining fissures formed by high-intensity coal mining are easy to lead to the strong water-rich aquifer, and it is very easy to cause the destruction of the groundwater system in the overlying strata, the accident of water inrush and sand inrush is easy to happen, especially the height of coal caving is difficult to control in fully mechanized top coal caving mining under aquifer. In this paper, the system protection of overlying aquifer in extra-thick coal seam is taken as the research object, the protection of aquifer and the safety control of water-sand disaster are the research objectives, and the key technology of intelligent caving for overlying aquifer protection in extra-thick coal seam is developed, based on the technology of preventing and controlling water inrush and sand inrush in coal mine, the fundamental way of protecting the groundwater system above the extra-thick coal seam is obtained. An intelligent top-coal caving technology is developed and applied, including top-coal movement tracking system, multi-round memory caving method and system. Based on the precise exploration of hydrogeological conditions, the actual measurement of overburden failure height and the determination of top coal caving height, the intelligent top coal caving technology of multi-round coal caving is applied to Control the height of mining fracture zone. Taking the applied working face as an example, the hydrogeological fine exploration and drilling verification, the acquisition of overburden failure height and the intelligent top-coal caving technology are applied, the safety and precise control of water-sand disaster in overlying aquifer is realized in the process of mining, and the overlying strong water-rich aquifer is effectively protected.