This paper presents a distributed robust formation tracking control scheme for a team of mobile robots with parametric uncertainties and input constraints. First for each interacting robot whose dynamics are uncoupled, distributed optimal control problems are introduced. Then a distributed robust moving horizon control scheme is consequently formulated as on-line solving each constrained optimal problem synchronously at each sampling time. The optimal control problem includes the initial state of the model employed in the problem as a decision variable. It is also shown that the proposed control scheme guarantees closed-loop stability. Simulation is performed to illustrate the proposed control law.