Drought disaster is one of the most frequent meteorological disasters in the Gannan Plateau, which seriously affects agricultural and animal husbandry production and ecological environment security in this region. Monthly precipitation and air temperature data from 31 meteorological stations in the Gannan Plateau and its surrounding areas from 1973 to 2022 are used to characterize meteorological drought employing the Standardized Precipitation Evapotranspiration Index (SPEI), and the temporal and spatial distribution of drought and its variations on annual and seasonal scales in the Gannan Plateau are analyzed by using Mann-Kendall test and Sen’s slope estimation methods. Results show that the annual SPEI in the Gannan Plateau presented significant downward trend with an obvious turning point in 1986, and the whole Gannan Plateau tended to be dry in the past 50 years. There were seasonal differences in the variation trend of drought, and the trend of drought intensified in summer and autumn, but in spring and winter it mitigated. In addition, there were spatial differences in the trend of annual and seasonal SPEI. In summer, it presented drought intensification trend in the middle and eastern regions of the Gannan Plateau, and in spring it showed similar to that in summer, but the area and degree of drought intensification were obviously smaller than that in summer. While in winter, it showed drought decreasing trend in the whole region. There were obvious spatial differences in the frequency of drought with different levels in the Gannan Plateau at the annual and seasonal scales. Light drought occurred frequently in the central and eastern parts of the Gannan Plateau, while medium and severe drought occurred frequently in the southern part of the Gannan Plateau, and the frequency of serious drought was less across the whole regions. Overall, the frequency of drought in the western was less than that in the central and eastern parts of the Gannan Plateau.