Abstract: The factors affecting the sustainable development of urban water resources are analyzed, the index of water resources sustainability evaluation is constructed and the Normal Cloud Model based on entropy weight is established to evaluate the sustainability of water resources. The spatial differences of water resources sustainability in 9 cities in the Guangdong Pearl River Delta Economic Zone, referred to as Pearl River Delta, which is water-rich and economically developed, were analyzed and quantified. The result shows that the sustainability of water resources in the Pearl River Delta is fair on the whole. Specifically, the water resource sustainability of cities in the east is better than that of the cities in the west. And the water resources sustainability of near-sea cities is higher than that of ci-ties far from the sea. The spatial difference of water resources sustainability is mainly due to the water resources endowments in the Pearl River Delta. Besides, the economic and social development also has a certain impact on the sustainability of urban water resources.