Abstract: For improving the thermal stability of magnetic multilayers, the interdiffusion of Ni₈₀Fe₂₀/Mo multilayers between 343~683K has been studied by determining the effective interdiffusion coefficient D_λ. The much lower activation enthalpy of diffusion is attributed to the coherence strains existing in the multilayers. As the annealing temperature is below 483K, this result suggests that the Ni₈₀Fe₂₀/Mo multilayers have a strong resistance to the atomic interdiffusion between sublayers. It is significant to application of NiFe/Mo multilayers.