Based on the background of rising temperature,changes in precipitation and its pattern,and increased vegetation coverage and biomass,the changes in global water resources have attracted widespread attention and concern.This paper analyzes the long-term data of river discharge,normalized differential vegetation index(NDVI),annual mean temperature and annual precipitation in 2 894 watersheds around the world.Results suggest that for the monthly mean discharge within the year(MQ),the proportion of watersheds with the trend of increasing,decreasing and not significantly changing is 9.1%,12.4% and 78.5% respectively;for the lowest monthly mean discharge(LQ),the corresponding proportion is 24.1%,11.7% and 64.2% respectively;and for the highest monthly mean discharge(HQ),the corresponding proportion is 6.4%,13.6% and 79.9% respectively.On regional(continent and latitude belts) and global scales,LQ decline and HQ rise are not found,MQ decline is associated with HQ decline,and MQ rise is associated with LQ rise,which indicates that the water resources quantity and annual distribution on regional and global scales have been improved in the past 60 years.Further analysis shows that climate change is the main factor leading to changes in water resources and annual distribution.However,different from the monthly extreme discharge(LQ or HQ) changes in a year,most of the months in which the monthly extreme discharge occurs have changed significantly.This change may have a profound impact on society and natural ecosystems,as well as production and lifestyle that rely on natural rhythms.