  A direct WIMP (Weakly Interacting Massive Particle) detector with a neutron
veto system is designed to better reject neutrons. An experimental
configuration is studied in the present paper: 984 Ge modules are placed inside
a reactor neutrino detector. In order to discriminate between nuclear and
electron recoil, both ionization and heat signatures are measured using
cryogenic germanium detectors in this detection. The neutrino detector is used
as a neutron veto device.The neutron background for the experimental design has
been estimated using the Geant4 simulation. The results show that the neutron
background can decrease to O(0.01) events per year per tonne of high purity
Germanium. We calculate the sensitivity to spin-independent WIMP-nucleon
elastic scattering. An exposure of one tonne $\times$ year could reach a
cross-section of about 2$\times$$10^{-11}$ pb.
