  Radiation pressure affects the kinetics of a system exposed to the radiation
and it constitutes the basis of laser cooling. In this paper, we study {\it
matter-wave pressure} through examining the dynamics of a quantum-classical
hybrid system. The quantum and classical subsystem have no explicit coupling to
each other, but affect mutually via a changing boundary condition. Two systems,
i.e., an atom and a Bose-Einstein condensate(BEC), are considered as the
quantum subsystems, while an oscillating wall is taken as the classical
subsystem. We show that the classical subsystem would experience a force
proportional to $Q^{-3}$ from the quantum atom, whereas it acquires an
additional force proportional to $Q^{-2}$ from the BEC due to the atom-atom
interaction in the BEC. These forces can be understood as the {\it matter-wave
pressure}.
