In order to study the uncertain nonlinear jamming problem in UCAV’s flight control system, a method using jamming observer to check the system’s jamming was designed. Based on jamming observer, a flight control law was constructed, which reduced the restrictive condition for the jamming. The simulation results show that the adaptive flight control law based on jamming observer, make UCAV’s flight control system have good stability and robustness, it’s a great convenience analyzing the system stability.