Abstract: The interrelationship between the thermal conductivity and lattice mismatch of the supevlattice interface is studied by non-equilibrium molecular dynamics（NEMD） method.The reason why lattice mismatch can minimize thermal conductivity is analyzed.The simulation is conducted in the system with temperature gradient and fixed period.Heat flux modification and layering analysis is adopted to assure system stability.Simulation results show that the mismatched crystal lattice on the boundary contributes to the reduction of thermal conductivity of superlattice thin film under certian temperature.The results also show that the thermal conductivity can reach the minimum when the lattice mismatch reaches a special value.According to preliminary analysis,that is because of the difference of phonon spereading mode.