Water resources occupies an extremely important position and role in urban development. This article uses Beijing Statistical Yearbook and Beijing Water Affairs Statistical Yearbook to analyze 2010-2018，especially since the South-to-North Water Diversion Middle Route entered Beijing in 2014. Changes in water resources. The data shows that with the continuous increase of water supply in the Middle Route Project of the South-to-North Water Transfer Project，the improvement of water-saving technologies and water-saving capacity，the total amount of water resources in Beijing has been increasing，the water supply structure has been continuously improved，and the urban sewage treatment capacity and water environment treatment capacity have been improved year by year In addition，with the implementation of Beijing’s strategy of “relieving non-capital functions”，the permanent population is no longer expanding rapidly，and the population pressure on water resources has been relieved to a certain extent. But on the other hand，although the growth rate of Beijing’s permanent population has slowed down and declined，the population base is huge，and with the improvement of living standards，domestic water consumption and its proportion continue to increase，and Beijing’s water saving space is getting smaller and smaller.，The problem of reclaimed water safety still exists，and the problem of water shortage in Beijing will still exist for a long time.