As the most important component of the cryosphere with the largest seasonal and spatial variations, snow cover is a vital fresh water resources in the Tibetan Plateau (TP) and downstream regions, and also a significant indicator of climate change in the TP and its surrounding areas. Therefore, under global climate warming the variation of snow cover over the TP is concerned by international scientific community. In this study, the spatial and temporal variations of snow cover days are analyzed based on the observation data from 94 meteorological stations on the Tibetan Plateau for the period from 1981 to 2010. The main results are as follows: (1) there was a very significant decreasing in annual mean snow cover days over the TP with a rate of 4.81 days decade~(-1)in the last 30 years, in which the decreasing rate was most obvious in winter, 2.36 days decade~(-1), followed by spring, 2.05 days decade~(-1), and the least decreasing rate was found in summer (0.21 days decade~(-1)); (2) the abrupt climate change of snow cover days occurred around 1997 and the most of less annual snow cover days were found in the later 10 years, especially in 2010, an anomalous snowless year; (3) over the last 30 years, 91.5% of the stations had experienced a decrease in snow cover days, especially in alpine regions of the TP interior and its eastern areas and south slopes of the southwestern Himalayans, where there were the longest snow cover days on the TP in the historic snow observation records, and increasing trend was only found in several stations in Qaidam Basin and its surrounding areas; (4) there was a great spatial variation in snow cover days on the TP due to the differences in geographic location, topography, surface feature, regional climate and elevation of the meteorological stations and the impact of atmospheric circulation etc. The areas of snow cover days more than 100 days were mainly located at the interior of the TP and its eastern regions; the shorter snow cover days, less than 5 days, was mainly distributed in the dry and warm valleyes of the southeastern TP.