Abstract: Basing on the daily data from the meteorological stations of the Tibetan Plateau, the characteristics of onset-to-end period and rainfall amount of the wet season were analyzed under the background of climate warming, using the method of pentad rainfall steadily passing the critical thresholds to determine the onset and end of the wet season.The characteristics of the onset-to-end time and the rainfall amount for different grades in the wet season were compared before and after warming periods in Tibetan Plateau.The results show that the wet season in Tibetan Plateau begins on the third pentad in May and ends on the sixth pentad in September.The total duration of the wet season is 28 pentads.The precipitation in the wet season concentrates from mid-June to mid-September.The three peaks occur in early July, late July, and late August, respectively.Among them, early July is the main peak in the wet season.The precipitation amounts in the wet season from 1961 to 2017 show an increasing trend in Tibetan Plateau.For spatial distribution, the precipitation amount decreases from southeast to northwest, and the precipitation amount in the Hengduan mountains located in the southeast of the plateau is most.The average temperature in the wet season increases significantly since 1997.There is an obvious difference among regions for the onset-to-end period of the wet season before and after warming.The onset of wet season delays significantly in the west part of the Plateau after warming periods.For most parts of the Plateau, the onset of wet season advances, and the end-date delays for most parts of the Plateau.After warming, the number of days that the precipitation is above the moderate rain grade increases.The extreme precipitation amount in the wet season significantly enhances, and its extent expands.