The stability and reliability of UAV data link is one of the important guarantees to ensure the full play of military and civilian effectiveness. Aiming at the propagation loss in the design of a UAV data link, free space loss, atmospheric absorption loss, and variability loss were studied in this paper based on the ITU-R P.528 model. The relationship between loss values and frequency, distance, and height was obtained. According to the propagation loss calculation method proposed in this paper, the propagation loss in typical UAV application scenarios is calculated and analyzed. Compared with the traditional calculation model, the present method can obtain more accurate results, which is important for the development of UAV data link equipment.