  The complete description of neutrino oscillations require the wave packet
treatment. For terrestrial experiments the contribution from the interaction of
neutrino with the Earth matter would modify oscillation pattern, i.e., the
dependence of the flavor transition probability on baseline $L$ and energy $E$.
We thus combine the wave packet approach and the matter effects, in order to
have more accurate descriptions of neutrino oscillation. The general expression
for the transition probability of oscillations with arbitrary numbers of
neutrinos are derived. As an example the two-neutrino oscillation is studied in
detail.
