A microscopic theory for viscosity and particle‐diffusion of the particle‐dispersions in polymers is presented. The theory is based on the scheme of ‘‘microscopic boundary layer,’’ which appropriately combines the statistical mechanical description of the microscopic response in particle‐polymers interface with the continuum mechanical description of the collective response in the polymer background beyond the interface. While the resulting theories in large particle limit correctly recover the continuum mechanical results for intrinsic viscosity and particle diffusivity, the theories for small particles show significant deviation from the continuum results and reasonable dependence on interface structure.