Abstract: The watershed over-standard flood is an extremely rare event, and the existing research is seriously insufficient. In order to understand its laws, this article reviews and describes the characteristics of watershed over-standard floods that have occurred in history from three dimensions of heavy rain, flood, and flood disaster. These extreme flood events include 1153, 1227, 1560, 1788, 1860 and 1870 floods in the Jingjiang section of the Yangtze River Basin, the 1730, 1957 and 1974 floods in the Yishusi River Basin of the Huaihe River, and 1794 and 1998 floods in the Nenjiang River Basin. The results show that(1) the over-standard flood in the river basin has rain characteristics such as wide and stable rain area, heavy intensity of rainstorm, long duration of rainfall, and large amount of accumulated rainfall.(2) It also has the flood characteristics such as bad flood encounter in the space, high flood peak and large volume and long duration of higher water level.(3) The disaster condition is characterized by wide disaster range, large disaster loss, and serious water damage to projects. This study has important guiding value for revealing the connotation of watershed over-standard flood, guiding the response of the “black swan” event of over-standard flood, and ensuring the safety of rivers.