The PR China has been very fast developing its energy sector in order to sustain its impressive economic growth. China's installed hydropower capacity is not only the highest in the world; it also shows a globally unique dimension in growth and dynamic. The southwestern province of Yunnan has one of the highest hydropower potentials within China. Its development makes the province one of the key suppliers of electric energy in China, supplying the economic and energy hungry load centers of coastal China but also Southeast Asia. In a decade Yunnan will have an installed hydropower capacity that exceeds that of Canada or the United States. The province is therefore often referred to as China's forthcoming (hydro-) powerhouse or as Asia's battery. Yunnan's rapid development is mainly based on large and prestigious hydropower projects along major rivers, often forming large reservoirs. Secondly it rests on centers of small hydropower development. They are based on small (sub-)catchments where SHP stations mostly form cascades of diversion type projects affecting entire watersheds. Both developments are creating hydroscapes. While Yunnan's large scale hydropower development is relatively well studied, there is an obvious research gap on Yunnan's small hydropower sector. But the latter has not only a huge relevance it also causes serious tangible cumulative implications. This rapid expansion of Yunnan's hydropower sector takes place in one of the most biologically, geographically and ethnically diverse regions in China. This creates a large need for careful management in order to avoid potentially significant environmental and social conflicts. Therefore the article shows the current status of Yunnan's ambitious hydropower development program including its political frame. It critically analyses the environmental and socio-economic consequences of both large and small hydropower projects. It further describes the transboundary implications and the relevance of the power grid.