Abstract. The wetlands of Argun River basin are important habitat for birds migrating between East Asia and Australia. Investigating spatial and temporal characteristics and evolution trends of water resources of this region is of significant importance for sustainable water management and coping with climate change. Using in-field data and NCEP (National Centers for Environmental Prediction) reanalysis data, the Mann-Kendall method and wavelet analysis method are applied to obtain the temporal characteristics. Spatial distribution analysis includes use of gridded data and data along the river. The results illustrate that water resources of upstream regions show descending trends, and the temporal distribution of the flow presents an “M” shape. Precipitation of this region has 10-year and 24-year scale primary periods. The period analysis is verified by the large flood in 2013, and forecasts that the next high flow year could be around 2021.