Abstract: Bituminous concrete is a typical multiphase discrete random medium. In order to study the propagation characteristics of ground penetrating radar wave in such medium, we based on random medium model theory and statistical method to study the spatial random distribution characteristic statistic, the volume percentage of material composition, autocorrelation function and its characteristic parameter (like autocorrelation length, autocorrelation angle) by core samples of bituminous concrete, and built corresponding three-dimensional models based on the modeling algorithm of multiphase discrete random medium under quantization constrain developed in the paper. According to a commercial ground penetrating radar bow-tie antenna, the paper built its realistic three-dimensional model by using finite difference time domain, and carried out three-dimensional numerical based on multiphase discrete random medium. The result shows that the multiphase discrete random medium model not only completely and accurately describes bituminous concrete, but also describes other complex heterogeneous mixtures. Forward section of multiphase discrete random medium is consistent with the measured profiles and is conductive to the interpretation of the ground penetrating radar profile data in nondestructive testing of bituminous concrete.