Abstract: The reradiation interference wiresurface model was used to calculate the interference values on radio station from UHVDC power line. In the model,the steel tower was represented as a surface model,the ground wire was represented as a wire model, and the whole model was excitated by vertical polarization plane wave. The whole work frequency band of receiving station was calculated to determine the space interval which has actual protecting distance. Then the interval was gradually narrowed with dichotomy method until the interval size was within allowable value. As a result, the accurate protecting distance was acquired. With the firstgrade receiving station of AM broadcasting as an example, the reradiation interference protecting distance from UHVDC power line and station was calculated.