This paper studies the direct-current bus voltage control of direct-current microgrid systems under false data injection attacks based on event-triggered fixed-time sliding mode control. Firstly, the mathematical model of the direct-current microgrid system under false data injection attacks is established. Secondly, to save network resources, event-triggered mechanisms are introduced in the sensor-to-observer channel and observer-to-controller channel. Thirdly, since the system current is difficult to be accurately measured due to the constant power load disturbance and false data injection attack, a state observer is designed. A fixed-time sliding mode controller based on the observer is designed, and the upper bound of the system convergence time is obtained. Finally, a direct-current microgrid system with two constant power loads and an energy storage unit is taken as an example for simulation. The results that the proposed control method can effectively resist the influence of constant power load disturbances and false data injection attacks on the direct-current bus voltage and save network resources effectively.