China is undergoing a rapid transition from rural to urban dominated economy. Economy is booming, social structures are changing, ecosystems are stressed, and sustainability is challenged. We analysed the socioeconomic and environmental vulnerability of river systems that are entirely or partly located in the continental part of China. One-third of the mankind inhabit the area covered by this study. Six stress factors (governance, economy, social issues, environment, hazards and water stress) were analysed separately and in combination as an overall vulnerability. China's most vulnerable parts were found to be situated in the lower Hai and Yellow River basins, with their high population density, low water availability and high human footprint. The other water-stressed areas in the northwest showed high vulnerability, too, and so did the water-rich coastal areas due to high population density, natural hazards and high human footprint. We went beyond existing water stress and vulnerability studies in three dimensions. First, our perspective was highly multidimensional and thus very relevant in addressing China's water challenges in a realistic and multifaceted way. Second, we combined administrative and river basin scales and used an essentially higher spatial resolution than done so far. Third, we included the transboundary dimension, which is not customary. This is highly important since one billion people China's neighbouring countries, in basins that are partly in China.