Abstract: Based on the real-time and historical meteorological observation data from national meteorological stations in China, the climate characteristics of China during 2021 flood season (from April 1th to October 16th) were comprehensively analyzed. The results show that during the flood season of 2021, the climate characteristics of China are generally more rain and higher temperature, severe drought and flood, prominent climate anomalies, and frequent extreme events. Firstly, the characteristic of spatial distribution of precipitation in flood season was more in the north and less in the south. The rainstorm processes occurred frequently, with strong intensity and significant extremes. Secondly, the high temperature days in China were more than normal, and the Indian summer occurred in the south. Thirdly, the number of landfall typhoon was less than normal, and Typhoon "In-fa" had the longest detention time on land in China since 1949. Finally, the regional and phased meteorological drought occurred in the south and north simultaneously. From August 2020 to March 2021, La Nina occurred in the equatorial central and eastern Pacific with a moderate intensity. The convective activity in tropical western Pacific was abnormally active and played an important role in the northward of subtropical high. The warm and humid air flows from Northwest Pacific and Indian Ocean were strong and moved northward, providing abundant water vapor for precipitation in the north. At the same time, the meridional gradient of Eurasian circulation in middle and high latitude is large, and cold air activities are frequent, resulting in more precipitation in the north than normal.