Abstract As the largest water consumption sector, agriculture sector plays a significant role in water resources reallocating via economic trade. Different from previous studies focusing on the impacts of economic trade on water quantity, this paper concentrates on the impacts on the water quality. Grey water footprint (GWF) of agricultural sector is used for investigating the impacts of trade on water resources. In this paper, the regional virtual grey water of agricultural trade network was built based on the GWF and multiregional input–output analysis. The GWF for agricultural sector in each region was inventoried. Then GWF of agriculture embodied in monetary flows among regions were calculated using multiregional input–output analysis. The main results showed that Shandong, Henan, Heilongjiang, Inner Mongolia, and Hebei were the most critical regions for water resources. Besides, Zhejiang and Guangdong have saved a large amount of water by importing water resources through agricultural trade. While, Hebei, Heilongjiang, Anhui, Henan and Xinjiang are exporting a large amount of water resources. Moreover, the regions with developed economy and higher population are more dependent on agricultural imports. By identifying the critical node and pathway in virtual grey water trade, this paper aims to provide theoretical foundations for mitigating water pressure and reducing water pollution in economic trade activities.