Abstract: China's grain issue already becomes a hot topic in the world. This paper attempts to use the concept of the virtual water as a tool to analyze the virtual water flows with grain between China and other nations,as well as between the regions within China. Based on the grain supply and demand under the different development strategies in the future,the paper identi-fies the grain trade scale and makes a prospect for the virtual water trade condensed in grain. The result shows that North China exports a virtual water flow of 18.4 billion m³ to South China in 1999,which indicates North China plays an import role in en-suring China's grain security and socio-economic development. In the future China will face with the big pressure of the rapid growth in grain demand. To ensure the national grain security China has to depend on herself to solve the grain issue. To keep the high level of the grain self-sufficiency,the inter-basin water transfer project is not only an effective way to prevent North China from suffering water crisis but also an important strategy to ensure the country's grain security,keep the social stability and promote sustainable development. In the meantime,the virtual water trade can be as a supplement to ensure water security in water scarce region.