The obtuse dihedral structure plays an important role in the stealth characteristics of the target, but its bistatic characteristics are still unclear. The method of combining electromagnetic simulation and statistical modeling is utilized to analyze its bistatic scattering characteristics from the perspective of frequency domain, space domain, polarization domain and statistical distribution. Studies have shown that when the electrical size is small, the bistatic scattering enhancement characteristics are not obvious, and the probability density distributions of monostatic/bistatic Radar Cross Section(RCS) are very different; the bistatic RCS probability density distribution of co-polarization exhibits bimodal characteristics. For this reason, the Bimodal Lognormal Distribution Model(BLDM) is proposed. This distribution model has achieved an ideal fitting effect. When the electrical size is large, the co-polarized bistatic forward scattering characteristics are significantly enhanced, and the monostatic/bistatic RCS probability density distributions are similar, which conforms to the lognormal distribution and the chi-square distribution. The law revealed has reference significance for the utilization and detection of obtuse dihedral structures.