Abstract: Using computational graph to construct the electromagnetic model of some stealth plane,FDTD and electromagnetic simulation software(Microwave Studio) are adopted to calculate the RCS of this plane in HF and VHF band.The monostatic and bistatic RCS are considered under different polarization styles and different incident angle.The numerical results demonstrate that this stealth plane will express strong resonant frequency point,and low frequency radar has the potential to detect and track stealth target.