Abstract: :Headwater region of the Heihe river polymetallic mining area is located in the hinterland of Qilian mountain, with rich mineral resources,but sensitive and fragile geological environment, and assessment on the carrying capacity of geological environment is urgently needed before mineral resources development.Based on the analytic hierarchy process(AHP), seven important environmental constraint factors were selected as the evaluation indexes.The weighted average composite index model was used to evaluate the geological environment carrying capacity of research area.The results show that 7.13% of the geological environment carrying capacity of the area is weak, which is mainly distributed in high altitude of glaciers and mountains, especially watersheds and rivers; 64.91% of the regional capacity is relatively strong, distributed at relatively low altitude, low slope of the low mountains, hilly areas, valleys and plain areas; the remaining of the regional capacity is moderate.Annual precipitation and vegetation coverage are the main factors influencing the carrying capacity.This study could provide the basis for the reasonable planning and development, geological environment protection, social economy coordinated development of mineral resources in headwater regions of the Heihe river.Besides, it could provide the method and reference for the study of geological environment carrying capacity in similar mining area.