In high-level radioactive waste disposal repository,radionuclides migrate with groundwater due to the intrusion of groundwater.Dispersion phenomenon will inevitably happen due to different velocity of seepage flow in porous media.As a highly toxic radionuclide,~(99)Tc dispersion degree in granite is a important basis for safety In high-level radioactive waste disposal repository, radionuclides migrate with groundwater due to the intrusion of groundwater. Dispersion phenomenon will inevitably happen due to different velocity of seepage flow in porous media. As a highly toxic radionuclide, ~ (99) Tc dispersion degree in granite is a important basis for safety