A novel interface shell element (ISE) based on variable-node element formulation is developed in this study. Explicit forms of shape functions for an n-node quadrilateral master element with additional nodes on the top edge are presented. The assumed natural strains in the form of the mixed interpolation of tensorial components (MITC) approach are employed to avoid the transverse shear locking and the membrane locking when the thickness of shell tends to very small. Numerical experiments show that the ISE gives excellent performance for coupling non-matching shell meshes.