Abstract: The paper aims to study the drought changes in Tibet. The evolution characteristics of the frequency of drought and severe drought in dry season and rainy season in the Tibet Region were analyzed based on the standardized precipitation index (SPI) as a drought index with the data of monthly precipitation of 38 ground meteorological stations during the period from 1981 to 2013. The results showed that: the drought frequency of the southeastern area was high in the dry season, drought frequency of the western area was high in the rainy season. The severe drought of the central and eastern area had high frequency in both the rainy season and dry season. The frequency of drought and severe drought in the dry season was the highest in the 1990s, and that in the rainy season was the highest at the beginning of the 21st century. The evolution of drought intensity in Tibet showed that the southern edge of Tibet had the most dramatic changes.