Decoupling water pollution from economic growth is the key to drive the coordinated and sustainable development of water resources and economy. Based on the Environmental Kuznets Curve (EKC) and Tapio decoupling theory, the grey water footprint (GWF) of 11 provincial areas along the Yangtze River Economic Belt (YREB) from 2003 to 2018 was firstly calculated. Then, an econometric model was constructed to identify the EKC pattern of the GWF and economic growth. Finally, the two-dimensional decoupling analysis was conducted hierarchically by combining the EKC hypothesis and improved Tapio model. The results showed that: The GWF varied significantly among provinces in the YREB. Except for Yunnan, the GWFs of other 10 provincial areas showed an overall downward trend. The EKC of GWF in the YREB presented an N-shaped change, and the per capita GDP at two inflection points were 36,700 CNY and 103,400 CNY, respectively. The proportion of agriculture and the degree of opening played a significant positive impact on the GWF. Except for pseudo-decoupling in Jiangxi, Chongqing and Guizhou, there were 7 kinds of two-dimensional decoupling states between GWF and economic growth in the other 8 provincial areas. Provinces with high levels of economic development have achieved more strong decoupling, while those with low levels of economic development have achieved more weak decoupling. This study not only expands decoupling theory and research methods for sustainable development, but provides pivotal implications for promoting the high-quality economic development of the YREB.