A link margin analytic modle is built for aeronautical VHF communication in order to analysis the influence of aircraft position and attitude and frequency on link margin. The radiation quality of the one-body of airborne antenna and aircraft is calculated. The main software program is designed based on MATLAB. The polarization attenuation and space attenuation between the transmitter and receiver can be calculated along with the change of the aircraft position and attitude and frequency. The change of the link margin of aeronautical VHF communication is validated in the last paragraph of the article. The system is very practicable.