This article aims at the radiation property of the electromagnetic sources buried in heavy rainfall. Based on general Maxwell equations and analytical analysis, the Lorentz gauge of the anisotropic medium is proposed, the non-homogeneous wave equation of vector potential is obtained, the exact solutions of the vector potential of these medium are obtained, and their validity is proved. The radiation field of the current element in the anisotropic medium is obtained. When the anisotropic medium is changed into the isotropy material, the radiation field obtained is consistent with the available references. Based on the anisotropic parameters of gypsum crystal and heavy rain medium, the radiation characteristics of current element are physically simulated and analyzed. It is found that the anisotropy of the medium has a significant effect on the electromagnetic source radiation and the radiation of the electromagnetic source in heavy rainfall has the weak anisotropy.