The major problems of the Weihe River include shortage of water resources, serious water pollution and loss of water and soil. The ecological basic flow of Baoji Section, Weihe River was 10m3/s. Based on it, quantitative analysis on the ecological basic flow of this section has been done. It shows that the effect of Baojixia Irrigation water diversion on the Weihe River is the main influence factor. The guarantee measures are rational use of water resources and water saving, management and policies, and water transfer projects.