So far the application of method of lines is restricted to electromagnetic boundary value problems （EM BVPs） in rectangular or compound rectangular regions with straight line boundaries.In this paper

a model of method of lines for 2-D EM BVPs defined in regions with curved boundaries is established based on the same method for EM BVPs in compound rectangular regions.The cut-off wavelengths of dominant mode in rectangular-to-circular waveguide transition and the equivalent circuit parameters of rectangular waveguide E-plane bends are calculated.The method is verified by the obtained numerical results.It is shown that the method possesses some advantages such as easy formulation and less computation time.