This paper investigates group consensus for the first-order multi-agent systems with nonlinear input constraints. And group consensus protocols for discrete-time and continuous-time multi-agent systems are proposed. By using the tools of the Lyapunov function, LaSalle׳s invariance principle and graph theory, group consensus/finite-time group consensus conditions are obtained. Finally, two simulation examples are provided to illustrate the effectiveness of our proposed methods in the paper.