Abstract: In this paper, a novel hybrid approach is proposed in which Iterative Physical Optics (IPO)subdomain splicing technique is combined with edge-based finite element method. It is applied to the analyses of electromagnetic scattering characteristics of electrically large complex cavities. IPO approach is applied for the region where it is suitable to use high frequency method; the edge-based finite element method is employed for the region where complex structures or complex materials are located. At the interface, the field continuous condition is applied to realize the coupling of the two regions. To verify the new approach, an open-ended empty rectangular cavity and cavity loaded with a metal cuboid are analyzed. The numerical results are in agreement with the published data and those obtained by FDTD. Good convergence behavior is observed. Moreover, complex cavities where three layers of lossy dielectric or a metal cuboid is loaded at the bottom are analyzed. The results show that the proposed hybrid approach is efficient for analyzing the electromagnetic scattering characteristic of electrically large complex cavity.