Water, energy, food, and ecology are essential for human survival and development. The Yangtze River Delta is one of the most important regions for China's sustainable development. It is of great significance to study the coupling coordinated development level of water-energy-food-ecology in the Yangtze River Delta for sustainable development. In this study, we establish the water-energy-food-ecology (WEFE) coupling and coordination development index system. Then, we analyze the degree of coupling coordination (DCC) of WEFE based on the coupling coordination evaluation model and projection pursuit model. The results show that the DCC of WEFE in the Yangtze River Delta shows obvious spatial-temporal characteristics. From the temporal view, the DCC in the Yangtze River Delta has shown an upward trend; from the spatial view, the DCC of Jiangsu, Anhui, and Zhejiang is higher than that of Shanghai.