The study is aimed to perform dynamic modeling of the part-feeder powered by piezoelectric actuation. This part-feeder consists mainly of a horizontal platform vibrated by a pair of parallel piezoelectric beams. The parts to be transported on the platform march forward owing to their intermittent impacts on the platform. The dynamic modeling technique used herein is essentially the Rayleigh-Ritz method, which first incorporates material properties and constitutive equations of the piezoelectric materials, and then captures the complex dynamics of the parallel-beam piezo-feeder by three lower-order assumed modes in the transverse direction of the vibrating beams. With the three approximated assumed modes in hand, the system dynamics is then represented by three coupled discrete equations of motion. Based on these equations, displacement and velocity of the platform can be approximately obtained. Based on the approximated motions of the platform, the marching speed of the parts with intermittent impacts on the platform can be predicted. Numerical computations are conducted to acquire the estimated marching speed of the parts, along with the experimental study. The comparison between the theoretical predicted transporting speed of the part and the experiment counterparts.