According to the characteristics of the airborne avionics system, a method for evaluating the RF(radio frequency) stealth performance of the airborne avionics system was presented. The factors that influence the performance of the airborne avionics system in the polarization domain, wave domain and energy domain were analyzed, the RF stealth index of the waveform domain, polarization domain and the energy domain were constructed, an RF stealth evaluation method of the traditional “radiation reception” model was broken. And a quantitative evaluation method of radio frequency stealth based on the working state and working parameters of airborne avionics system was established. Finally, a simulation evaluation of airborne radar system was carried out. Results show that the proposed method can correctly reflect the RF stealth performance of airborne radar system.