This paper investigates the distributed event-based controller to deal with the leader-following consensus tracking problem of linear multi-agent systems with fractional-order dynamics. By designing effective distributed event-triggered mechanism, every agent determines when to send local status information to its own neighbors, to relieve the communication burden of network. Given by the impact of fractional-order dynamics, we use the fractional Lyapunov method to obtain a sufficient condition, which guarantees that each follower can keep up the designated leader. Besides, the feasibility of control strategy is guaranteed by providing a positive lower bound on the triggering interval, which excludes the Zeno behavior. Lastly, a numerical simulation is presented to validate proposed strategy.