Based on the actual terrain and meteorological conditions, a method of extracting high-precision elevation data on an arbitrary terrain path from a three-dimensional digital earth is achieved by interpolation, and combining with atmospheric refractive index model and parabolic equation model, the propagation loss of electromagnetic waves in any terrain profile is calculated. The energy coverage of a monostatic radar at a certain altitude of space is computed. The simulation results show that the method proposed in this paper can deal with effects on radar energy coverage caused by both meteorological and georaphical factors, and better exemplifies the propagation effects of electromagnetic waves while comparing with human visual range. It provides a reliable technical approach for predicting radar energy coverage in complex meteorological and geographic environments effectively.