The system-level cable coupling characteristics of UAVs are of great significance for the analysis of electromagnetic effects and mechanisms of UAVs. A field-circuit co-simulation model for electromagnetic interference of the multi-typed cables in UAVs is established and the coupling characteristics of the cables are analyzed. Moreover, considering the complex physical structure of the UAVs, studies on the system level cable coupling characteristics of the UAVs are carried out. Based on the surface current distribution of the UAV system, voltage monitoring points are set up at the UAV flight control port cables, wing cables, and rotor cables to monitor the voltage distribution of the UAV system cables, thus the weak links of the UAV system cable coupling are obtained. The simulation results show that when the plane wave is incident into the same length of cable at different angles, the coupling peak voltage is the largest when the electric field vector is parallel to the direction of the cable, and the coupling sensitive frequency point of different types of cables is the same; when the plane wave incident into different lengths of cable at the same angle, the reciprocals of the resonant frequency points satisfy the same multiple relationship as the cable lengths. In the actual UAV system cable irradiation scenario, the sensitive frequency band of flight control cable coupling is 300-600 MHz. The sensitive frequency band of the coupling of the UAV wing cable and the rotor cable is 300-430 MHz, and the peak voltage of the coupling of the flight control cable is significantly greater than that of the wing cable and the rotor cable.