In this paper. A dynamic hybrid control method is proposed for constrained flexible manipulators. Based on the assumed mode method, we derive the dynamical equations of a constrained two-link flexible manipulator. Then we divide it into slow subsystem and fast subsystem via singular perturbation method. For the slow subsystem, we present a hybrid position/force control method basing on the feedback of force. For the fast subsystem, we design a controller basing on optimal theory. Simulation results prove the effectiveness of this method.