Abstract: To implement the numerical analysis of multi-scale electric-large problem with multi-layer thin dielectric shell, a novel boundary condition of multi-layer thin dielectric shell is proposed in this paper,which takes both the amplitude and phase change across the shell into consideration.The usage of this boundary condition may avoid the singularity caused by the mesh of the thin shell, and then the multi-layer dielectric radome is analyzed numerically.As an example, the influence of the multi-layer radome to the radiation of slot array antenna is evaluated.