Abstract: The flow field around groyne is of the 3D characteristic. In order to analyze the influence of the flow field and river bed scouring and silting on the polutant diffusion,the dynamical compressive models of water and suspended sediment are derived with the volume of fluid method. Considering the pollutant's adsorption and desorption actions,the 3D water quality models are established for soluble and absorbable pollutant in sediment flow. With calculation of the 3D flow affecting the non-submerged groyne,the comparison between calculative and experimental data means that the dynamical compressive models can accurately simulate the free surface and the flow field around groyne. The simulation of pollutant difusion around groyne shows that the backflow behind groyne slows the decay of pollutant concentration. The turbulence of water flow around groyne increases soluble concentration and absorptive capacity of the suspended sediment markedly under river bed scouring and silting conditions.