The invention discloses a measuring and calculating method of a grain production water footprint of a region. The method comprises the steps of obtaining crop sowing area, an irrigation norm, grain output, irrigation water capacity, agricultural acreage, irrigation area, a multiple crop index, precipitation amount and crop growth period data of the region to be calculated, calculating a comprehensive irrigation norm of a grain crop and an industrial crop of the region to be measured and calculated, calculating the grain irrigation water capacity and blue water resource usage amount by a comprehensive irrigation norm allocation method, estimating effective precipitation of the region to be measured and calculated and calculating a total green water resource with an observed value of the decade precipitation amount, calculating a grain production blue water footprint and a grain production green water footprint of the region with blue water quantity, green water quantity and the grain output, calculating the grain production water footprint of the region to be measured and calculated and determining components of the grain production water footprint. According to the method, the grain production water footprint of the region can be measured and calculated directly from the actual input amount of the water resources, a result reflects the comprehensive utilization efficiency of the rainwater resource and the irrigation water resource in grain production, and the method offers help to the studying of water problems of the grain production.