The interaction between a screw dislocation and a circular nano-inclusion incorporating interface stress is investigated.The analytical expressions of the complex potentials and the image force acting on the dislocation are obtained by means of the complex variable method.The influence of interface properties and the size of the inhomogeneity on the image force is evaluated.The results show that the local hardening and softening effects at the interface of the nanoscale inhomogeneity due to the interface stress is remarkable and the additional repulsive/attractive force acting on the dislocation is produced.The normalized image force increases (decreases) with the decrease of the radius of the inhomogeneity, and the size dependence becomes significant when the radius of the inhomogeneity is reduced to nanometer scale which differs from the size-independent classical solutions.Our results are helpful in the understanding of the motion mechanism of the dislocation and relevant physical phenomena in nano-structured materials.