In June 2022, under the combined influence of the southwest monsoon and an upper-level trough, three rounds of heavy rainfall occurred in the Beijiang River Basin of Guangdong Province. The third round of heavy rainfall directly triggered the "2022 No.2 Flood" (referred to as the "22·6 Flood"), resulting in the most severe flood control challenge since 1915. By conducting extensive and in-depth field investigations and analyses of rainstorm-induced floods and associated disasters in the main stream and major tributaries of the Beijiang River, and through comparative analyses with historical floods. Flood frequency analyses at the control stations on the Beijiang main stream and its major tributaries were conducted. The "22·6" flood was systematically and scientifically evaluated as a catastrophic basin-wide flood exceeding a 100-year return period, with downstream river sections experiencing floods exceeding a 300-year return period. These findings provide solid and reliable support and a decision-making basis for future flood control and disaster reduction, as well as engineering optimization and scheduling. They also offer valuable insights for planning and construction in the Beijiang River Basin and its downstream Guangdong-Hong Kong-Macao Greater Bay Area