Abstract: Recently, the inversion of tropospheric duct refractivity from radar clutter (RFC), which is an electromagnetic inversion problem, becomes a hot spot of research. In order to reduce the uncertainty of inversion, this paper proposes a sea clutter model in evaporation duct environment by discussing the effect of grazing angle on radar sea clutter based on the horizontally inhomogeneous evaporation duct model. The effectiveness of the sea clutter model is verified by using the observed data. The results show that the inversion effect of RFC using the model is effectively improved.