Taking the virtual water for grains in China as the main research object, the LMDI index decomposition method is employed to decompose the driving effect of water consumption for grain production, and a quantitative study is carried out from the four key drivers of demand structure, grain production, economic development and population. The geoda software is used to obtain the Moran index to analyze the spatial correlation of food water use and the impact of various driving effects among provinces. Based on this, some recommendations are proposed for the current status of China's virtual water for grains.