Persicaria thunbergii is a representative annual herb in Korean wetlands, widely inhabits not only in lentic wetlands, but also in unstable riparian wetlands. To better understand the occupational strategy of this plant, we investigated environment, growth characteristics before and after harsh flooding disturbance in FDA (flooding disturbed area) and NDA (non-disturbed area). Water level, fresh soil moisture and organic matter of NDA were significantly higher than FDA. Before flooding disturbance, plant height, individual length, number of node, individual biomass and biomass per 1 $m^2$ were significantly higher in FDA than in NDA. After flooding disturbance, plant height, biomass per 1 $m^2$, coverage and relative coverage were significantly lower in FDA than in NDA, yet individual length, number of node, individual biomass and aerial seed production were not different. In FDA, creeping stems survive despite a flooding disturbance because they are parallel with the water flow and are firmly fixed to the ground through numerous adventitious roots. Surviving creeping stems make new shoots rapidly and P. thunbergii recovers its biomass during less than a month. Every regenerated shoots make reproductive organs. Thus, P. thunbergii can reproduce and successfully survive the next generation in the riparian habitat despite the harsh flooding disturbance every year.