A sliding mode load-frequency control (LFC) strategy based on an adaptive triggering mechanism is proposed for a multi-area interconnected power system with electric vehicles (EVs). Firstly, the integration of EV in the frequency control of the power system is considered, and the impacts of primary and secondary frequency control on system frequency variations are investigated. The effects of renewable energy fluctuations and load disturbances on system frequency are also analyzed. Then, an adaptive event-triggered mechanism is designed to improve network utilization and address transmission delays in the network. An asymmetric Lyapunov functional is established to prove the system's asymptotic stability, and a stability criterion with low conservatism is derived. Finally, the effectiveness of the proposed scheme is verified, and an optimization algorithm is used to design the optimal participation of EV in frequency regulation. The results show that the control strategy designed in this paper can effectively improve the frequency regulation performance of the system under renewable energy and load disturbance, and EV participation in both primary and secondary frequency modulation has a significant effect on improving the system performance.