A research concerning active residual vibration control of planar 3-RRR flexible parallel robots was presented. First, based on the finite element method and the Lagrange’s equation, the equations of motion of the smart beam bonded lead zirconate titanate (PZT) actuators and sensors were modeled. Considering constraint equations of rigid motion and elastic motion, the general motion equations of planar 3-RRR flexible parallel robots were determined by the compatibility. The high-order equations of the system in physical space were transformed into modal space through the modal theory. According to the low-order modal equations, both the strain rate feedback controler and the optimal state feedback controler were designed for suppressing residual vibration of the system. The numerical simulation results revealed that two kinds of controllers could effectively suppress residual vibration of the system. Moreover, comparing the strain rate feedback control, the optimal state feedback control could obtain better control results in a lower control voltage.