Based on the flood characteristics of Poyang Lake, this paper selects specific flood characteristic indexes,uses mathematical statistical methods to analyze the trend, mutation and periodicity of Poyang Lake's flood characteristic indexes, as well as the evolution characteristics and driving factors. The conclusions are as follows: 1) the possibility of high flood in the future is still large, and the annual maximum water level of Poyang Lake in the next 6～10 years is still in the wet season; 2) the flood distribution has changed greatly during the year, and the change process has evolved from ＂low level with long period＂ to relatively ＂high level with short period＂, and the water volume is more concentrated during the year; 3) there is an obvious increasing trend in the duration of high flood level, whose duration extends by 2.2 days in average each decade; 4) the periodic changes of annual maximum water level and annual average water level are mainly controlled by the periodic changes of ＂Five Rivers＂ entering the lake. At the same time, the original periodic change law will be changed by other factors. The annual maximum water level mainly changes every 5 years, followed by 40～49a as the second main cycle.