Flood and waterlogging disasters in plain river network region in recent years have brought about severe damage to people's lives and property safety. Rainfall is the key factor causing flood disasters in the region, of which the most typical ones are plum rain and typhoon rainstorm. The flood generating mechanism of plum rain and typhoon rainstorm varies because of different temporal distribution. In the aim of investigating the influence of rainfall's temporal variation on flood process, a 1D- and 2D-coupled hydrodynamic model of Wuchengxiyu hydraulic district of Taihu Lake drainage basin was built with MIKE 11 and MIKE 21. The model was calibrated and validated by several measured flood events. Numerical simulation of flood processes under different design conditions in the study area was conducted. The influences of magnitude, duration and temporal variation of rainfall on flood process were examined. Results suggest that the temporal distribution of rainfall has apparent influence on flood in plain river network. Rainfall of long duration is sensitive to the delay of rainfall peak, while rainfall of short duration is largely affected by the time variance coefficient. Meanwhile, rainfall amount has evident impact on both long-duration and short-duration rainfall.