In recent years, the control issue of unmanned aerial vehicle suspension transportation systems has become a hot topic in theoretical research and engineering applications. A control method for multiple quadrotors suspension transportation systems based on event-triggered formation optimization is proposed in this study, which reduces the power consumption of quadrotors by adjusting the formation of the quadrotors in real time. According to the expected force of the load, the optimal formation is obtained by constructing optimization algorithms, and the event-triggering mechanism is used to reduce the solving frequency. Furthermore, the backstepping method is used to design a cooperative flight control law. Both the stability of the closed-loop system and the boundedness of the number of event triggers in a finite time are demonstrated through the Lyapunov method. Finally, numerical simulation verifies the effectiveness of the proposed control method.