In this paper, an event-trigger based on adaptive fuzzy control algorithm is proposed for the trajectory tracking of quadrotor unmanned aerial vehicle (QUAV) with model nonlinearities and external disturbances. Dividing the QUAV system into position subsystem and attitude subsystem, fuzzy logic systems are used to identify the nonlinearities. Then, an adaptive fuzzy control law is designed based on backstepping technique, and an adaptive event-triggered mechanism is constructed simultaneously, which determines the event-triggered instants. Thus, the adaptive fuzzy control law and the fuzzy parameter adaptive law are updated in an aperiodic form. Based on Lyapunov stability theory, it is proved that all signals in the closed-loop system are ultimately uniformly bounded via the impulsive dynamical system tool, and the tracking error converges to a small neighborhood of the origin. Besides, it is proved that there is a positive lower bound between the inter-sample time to avoid Zeno behaviour. Finally, simulation results illustrate that the proposed control scheme can guarantee the trajectory tracking control of the QUAV system, while it is able to the update frequency of the controller and improve the resource utilization.