The formation mechanism， influencing factors and research techniques of internal pollution has been described.Environmental dredging has become the most widely used measure to control the internal pollution of water body.The function，related technology and evaluation methods of environmental dredging has been summarized.It has been reported that environmental dredging has negative effect on the watery condition improvement and watery living organisms.Results showed that choosing appropriate dredging depths，frequency and seasons can largely improve environmental dredging effects.To aigd in analyzing watery environments and improving hydrodynamic，mass balance，sediment particle transport and dispersion models，it is available to further reveal the transformation and migration mechanism of sediment pollution and establish effective environmental dredging strategy.