Abstract: On the Qinghai-Tibet Plateau, the occurrence and distribution of elevational permafrost and its dynamic changes and the seasonal freezing-thawing processes in the active layer are closely related to the recharge, flow paths, and discharge of groundwater. Therefore, permafrost controls or affects the hydrogeology on the plateau. As an aquitard, permafrost greatly limits the development, evolution, movement and hydraulics of groundwater, affecting the occurrence, dynamics and circulation of groundwater. In addition, permafrost can modulate the hydrogeological cycles by forming and changing the storage of ground ice and groundwater through moisture migration, ice segregation, and ground ice structures and textures in permafrost. Under a warming climate and with increasing anthropogenic activities, significant permafrost degradation has been observed and more dramatic degradation of permafrost is anticipated. These changes may affect the ecology and hydrogeology in the permafrost regions with a series of hydrological and hydrogeological, ecological and environmental impacts. These issues urgently call for more systematic, long-term and in-depth research on the observations of, experiments on and modeling in permafrost and ecological hydrogeology on the plateau as a whole, and in several key regions or watersheds, such as the sources areas of the Yangtze River and the Yellow River, as well as in the upper reaches of the Heihe watershed on the northern flanks of the Qilian Mountains.