Abstract: The concept of virtual water is rich in the form and connotation of water resources, and Its value is reflected in, not only the virtual water trade taking population, grain and trade as a link, but also the social attributes. Based on the double value of virtual water, combined with the equilibrium data of national grain production and consuming, a linear optimization model was built to estimate the virtual water flow pattern of China’s inter-provincial grain trade. Then the comprehensive benefit caused by virtual water flow was analyzed from the aspects of resources, economy and environment. The result shows that the virtual water flow of China’s inter- provincial grain trade manifests the characteristics that the North water flows to the South. It is complementary to the South-to-North Water Diversion Project of physical water. That realize the interflow of water resources between north and south. In terms of resource efficiency, the virtual water flow pattern of inter-provincial grain trade in China has saved 15.296 billion cubic meters of water resources in the whole country, accounting for about 15.79% of the total virtual water flow. What behind the surface water conservation is the anomalous phenomenon that water transfers from deficient area to sufficient area and that the serious problems of low utilization efficiency of water resources in the widespread water sufficient area. When it comes to economic benefits, the overall is increased, with industrial added value reaching 6.77 trillion yuan. The distribution of increased economic benefits on the contrary, the distribution of detracted economic benefits more dispersed, and the derogation of benefits requires the construction of regional compensation mechanism. Then we turn it to environment benefits, it is poor, and areas with high crop green water occupancy index output a large number of virtual water in the case of local agricultural ecological green water on overdraft. It will be a serious threat to the terrestrial natural ecosystems and restrict the development of local economy. According to the results, we can get some policy implications and provide new ideas for water resources management, regional development and ecological security. The policy implications include advocating water resource management method combined physical water with virtual water, constructing a virtual water compensation mechanism for coordinated regional development and maintaining ecological security with a  balance between green water and blue water.
Key words：inter provincial grain trade; virtual water flow; resource benefit; economic benefit; environmental benefit