Climate change is now remarkable in the source regions of the Yangtze River, and impacts the plateau ecosystem, particularly, on the heat-water processes of the active layer due to the change in water and heat balance between the permafrost surface and the atmosphere. For this reason, a simulated experiment of artificial warming on the heat-water processes of plateau ecosystem was carried out in experimental chambers without cover to simulate the mean annual air temperature increasing about 6.7 ℃ and 3.5 ℃. The experimental results were analyzed and compared with observation in an outdoor comparison sample plot in an alpine swamp meadow ecosystem from 2007 to 2008. It is found that short-term warming will promote plant growth and development, increase significantly the aboveground biomass, postpone the freezing beginning date, make the thawing beginning date in advance, and then shorten the duration of entirely frozen period. There was an obvious dry layer at 65-cm depth of the outdoor comparison sample plot, but the soil moisture decreases with depth in the warming chamber. However, there was an obviously middle dry layer in the warming chamber, which is familiar in the source regions of the Yangtze River. Moreover, experimental warming lead to an increase in topsoil water content due to poorly drained swamp meadow with higher organic matter content and thicker root horizons. Experimental warming makes the soil moisture fluctuating layer migrating down to 40-cm depth. The results of this study will have some contributions to study alpine cold ecosystem water-heat process and water cycle under climate change.