In order to comprehensively evaluate the regional water resources sustainability, a regional water resources sustainability evaluation system was constructed based on the composite system of water resources, social economy and ecological environment. The projection pursuit model and cloud model were used to reasonably assign the comprehensive weight of each index, and the normal cloud model was adopted to determine the index membership degree. Then, a regional water resources sustainability evaluation model based on the combined weight and cloud model was established to evaluate the status of water resources sustainability of nine cities in the Pearl River Delta. The results show that the water resources sustainability of the Pearl River Delta Urban Agglomeration showed an overall upward trend from 2007 to 2020, which has reached a preferable level by 2020. The spatial pattern of water resources sustainability in the region shows that the eastern cities are better than the western cities and the southern coastal cities are better than the far coastal cities. The levels of sustainability among the subsystems are not consistent, the ecological environment subsystem is at a good development level, whereas the water resources subsystem and social economy subsystem are the main factors causing the spatial difference of water resources sustainability in the Pearl River Delta Urban Agglomeration.