China has the richest hydropower resources in the world. Yunnan's exploitable hydropower resources rank third in China, second only to Tibet and Sichuan Province. Yunnan has experienced soaring growth in installed hydropower capacity in the past several decades. The fast development of hydropower makes the province one of the main producers and exporters of hydroelectricity. However, with inconsistencies between hydropower development and various related resources, more and more hydropower generation has been curtailed in recent years. The increasing curtailment of hydropower generation not only caused large-scale waste of sustainable energy, but also impaired the potential higher contribution of hydropower for GHG emission reduction. This paper provides an overview of the hydropower resources and their development in Yunnan and systematically analyzes the constraints causing the curtailment of hydropower generation. We argue that there are several constraining factors such as slowdown of economic growth, inadequate transmission capacity due to a weak grid structure, inconsistency between power grid companies and local government, and uneven distribution of precipitation seasonally and annually. Recommendations are made to alleviate or eliminate hydropower curtailment in Yunnan and other hydropower rich areas. (C) 2018 Elsevier Ltd. All rights reserved.