The flood often causes damage to human and the environment. In order to determine whether the flood can affect the bacterial community which plays an important role in the process of geobiochemistry, we collected the surface water samples along Daling River before and after the flood in 2012. We analyzed the bacterial community of the samples using DGGE, combined with statistic methods PCA and RDA. The results were as follows: (1) The flood had a great effect on the bacterial community of bacteriaplankton in the river. Before the flood occured, the PCA result showed that samples formed clusters according to their natural habitat types, while this relationship disppeared after the flood. (2)The bacterial community was primely shaped by pH and salinity which was determined in other studies as well before the flood, while the main explanatory environmental factor was total phosphorus after the flood. Therefore,we came to a conclusion that the flood can shape the bacterial community by the shift of the environmental characteristic such as total phosphorus.