南水北调工程已正式列入“十五”计划，近期南水北调工程主要是东线和中线开工建设。文章论述了大西线南水北调的必要性和研究路线；论述了采用数字地球虚拟仿真技术研究西南诸外流主河的调水可行性，包括调水量、地质基础、调水路线优化、环境效益的研究方法和研究路线。

The south-north water project have been listed in the Tenth Five-Year Plan. Recently the east line and middle line in this project have been ready to start working. In order to change the status of lacking water in north of China, this paper discusses the necessity and the feasibility of diverting water from the southwest trunk rivers with the digital earth virtual technique, including the amount of water diverted, the geologic bedrock, the optimum line of diverting water and the impact on entironment.