Under the context of global warming, understanding of spatio-temporal variation of snow depth on the Tibetan Plateau (TP) is particularly important because climate observations in high-altitude regions have shown more sensitivity to climate change. The snow depth on the TP, as one of key components of cryosphere, is related to water availability downstream of major river basins in Asia and its anomalies may potentially affect subsequently regional weather/climate and monsoon systems over eastern and southern Asia through mechanical forcing and changing surface heat and moisture fluxes. Therefore, in this study, the spatio-temporal variation of snow depth on the TP is analyzed using observation data from 94 meteorological stations for the period from 1981 to 2010. The main results are as follows. (1) The highest snow depth record mainly takes place in the southern Himalayas Mountains and the lowest snow depth is found in dry-warm valleys in southern TP and Qaidam Basin in the northern TP. (2) There is a significant decreasing trend in annual mean maximum snow depth on the TP with a rate of 0.55 cm every 10 years in the last 30 years and abrupt climate change of snow depth from high to low occurs around 1997. (3) On seasonal scales, mean maximum snow depth in spring also has a very significant decreasing trend at a rate of 0.47 cm every 10 years, and abrupt climate change of snow depth in spring from high to low occurs around 1998. In autumn and winter, the decreasing trend in mean maximum snow depth is not noticeable. At a specific station, the changing trend of snow depth varies from region to region. In autumn, snow depth decreases at 56% stations but increases at 31% stations on the TP. In winter, the decrease in snow depth occurs at 61% stations and stations with higher decreasing rate are primarily distributed in the southwestern TP while the increasing trend of snow depth is found at 31% stations, which are mainly located in eastern part of the TP. In summer, snow cover on the TP is very scarce, primarily distributed in alpine region of high altitude and latitudes. Over the last 30 years, the decreasing trend of snow depth in summer is also significant.