Abstract: Floods can have disastrous effects on the society and environment, and scientific research can help to mitigate these effects. So far, not enough attention has been paid to the floods over the arid and semi-arid regions in China, and the awareness and prevention policy on floods over these regions are relatively weak. The floods over the arid and semi-arid regions are highly associated with the number, intensity and duration of extreme precipitation events, which also determine the number and severity of the flood events and their secondary geological disasters over the regions. In this study, we analyzed the number and characteristics of extreme precipitation events over the arid and semi-arid regions in China, in order to provide some scientific basis for making prevention policy. The results show that the number of days of extreme precipitation events has increased since the 21st century over the arid and semi-arid areas west of 110°E, but decreased to the east of 110°E. The trend of extreme precipitation showed positive sign in the area west of 110°E and negative sign in the one east of it. In addition, the fraction of the extreme precipitation change over the total precipitation one is over 40% in most of the regions, and reached 50% or even 100% to 200% in some areas. The seasonal variation showed that the extreme precipitation increased in spring over the north of the Tian Shan Mountains, southern Xinjiang, northern Dunhuang, northern Gansu, and Inner Mongolia. In summer, the extreme precipitation increased dramatically over the arid and semi-arid regions west of 110°E; in autumn, the extreme precipitation increased over Yulin in northern Shanxi, Erdos, Hohhot, and Baotou in Inner Mongolia, and some other places. Based on the above results, we carried out more basic analysis of the spatial and temporal characteristics of floods over the arid and semi-arid regions.