This paper studies the group consensus of a class of heterogeneous multi-agent systems composed of the linear first-order, second-order and the nonlinear Euler-Lagrange agents. A class of control protocols to solve the group consensus problem is proposed, and we extend the protocol to sufficient cases including systems with leader-following network. Combining graph theory and Barbalats Lemma, we construct Lyapunov function to prove group consensus. Finally, numerical simulation results are given to illustrate the accurateness of theoretical results.