Meteorological target simulation using polarization information is the foundation of the theoretical research and design application of dual-polarization Doppler weather radar. Currently, the theoretical research of airborne dual-polarization weather radar is in the development stage. To provide high-fidelity simulation data required for airborne dual-polarization weather radar detection technology, in this study, a simulation method of the polarization characteristics of rainfall determined using airborne weather radar based on numerical weather prediction is proposed. The numerical weather prediction model is used to realize the modeling and simulation of meteorological scenarios and provide information on meteorological parameters such as temperature, particle concentration, and mixing ratio of rainfall. In the analysis of the microphysical properties of rainfall, the electromagnetic scattering matrix is calculated and the simulation of the polarization characteristics of rainfall is achieved. The simulation results for different microphysical property parameters have led to the establishment of a high-fidelity rainfall model and demonstrated (via comparison with the real radar data) that the simulation of polarization characteristics using the proposed method is effective and reliable.