Abstract: We propose a consensus algorithm based on event-triggered control to save on resources. The proposed algorithm is meant to solve the average consensus problem of second-order multi-agent systems under an undirected network with fixed topology. First, for each agent, we design a trigger function with respect to the state error. An agent triggers an event only when the state error reaches a specific value, and the control input is constant between two adjacent event triggering times. Next, by employing the model transformation method, the consensus problem of the multi-agent system is converted into the stability problem. Then, some sufficient conditions for the average consensus of the systems are provided by using matrix theory and Lyapunov theory. Finally, numerical simulations are used to verify the effectiveness of the proposed theoretical scheme.