As rapid warming and consequent glaciers retreat across the Tibetan Plateau (TP), the problem about whether or not atmospheric water supply could alleviate the depletion of surface water storage need to be examined. Long-term changes of atmospheric water vapor balance across the TP is investigated by the ERA5 reanalysis from 1979 to 2018.Annual accumulated precipitation, water vapor convergence and evaporation generally keep an equilibrium but with different long-term variation trends: 0.68mm/a, 0.68mm/a and -0.18mm/a, respectively. Results suggest that surface water storage will not be well replenished by the water vapor transported from outside of the TP. For different regions of the TP, characteristic of water vapor balance and their long-term trends are completely different. Regions around Yarlung Zangbo Grand Canyon experiences sharp decrease in water vapor convergence and leads to decrease in precipitation. Meanwhile, evaporation keeps increasing due to the warming and melting of glaciers. Loss of surface water storage should be severe. For the source region of the Three Rivers, decrease in water vapor convergence overlaps increase in evaporations leads to no significant changes in total precipitations. Decrease in water transported from outsides brings risk to the depletion of surface water storage. Brahmaputra basin, inner TP and Qilian Mountain show significant wetting trends due to the increases in both convergence of water vapor flux and evaporation. Above regional characteristics of water vapor balances across the TP cause by inhomogeneous variation of atmospheric heat source and changes of atmospheric circulations, which need to be studied in further.