With the successful application for the list of the World Heritage, the renaissance and activation of the Beijing-Hangzhou Grand Canal has become a focus, of which, the key is utilization and distribution of water resources of watershed along the Grand Canal. This article adopts the A1B scenario of IPCC in order to simulate space and time distribution of precipitation as well as its evolution characteristics both in Chinese modern times (later 20th century, represented by 1981-2000 twenty years' annual mean value) and future times (middle 21th century, represented by 2041-2060 twenty years' annual mean value). This scenario simulation aims to analyze the space-timechange characteristics of water resources of the Grand Canal. It reveals that from north to south, the volume of water resources of the Yangtze River Valley will decrease, while that of Huaihe River Valley will increase significantly. And that of the Huanghe River Valley and the Haihe River Valley will rise up slightly. Therefore, it concludes that the key of navigationof the GrandCanal is to use as early as possible the water resources of the Huaihe River Valley to transfer water resources in the south valley of Huanghe River to the north valley, and achieve navigation of the Grand Canal in the north of Huanghe Valley as well as to restore the "diversion works in Nanwang" and "Northern five Lakes Reservoir" in the context of "South-to-North Water Diversion Project" so that the GrandCanal world heritage could be preserved.