Based on the coupling coordination model, this paper intends to use the panel data of 31 provinces in China from 2000 to 2019, analyze the coupling and coupling coordination relationship between environmental regulation and green water resource efficiency (GWRE), and explore the space-time pattern of coupling coordination. The results show that: (1) The overall level of environmental regulation in China is showing increasingly stringent characteristics, and the overall GWRE is showing an upward trend. Both show spatial differences, and there is a strong correlation between the spatial spillover of environmental regulation and the improvement of GWRE. (2) The environmental regulation and GWRE in China have not yet achieved the benign resonance goal of high coupling. It is overall manifested as a medium-coupled run-in and a medium-coupled coordination. (3) The space-time evolution characteristics are prominent, and the coupling coordination degree of different provinces (regions) shows a more significant difference, showing the spatial pattern of higher in the eastern region and lower in the west region. Therefore, some policy suggestions are put forward on how to break through the bottleneck of environmental regulation for the improvement of GWRE and how to optimize the external environment in which the government optimizes environmental regulation to inhibit the efficiency of green water resources.