A new relativistic method for calculation of particle-hole and Delta-h
ole excitations of the pion in nuclear matter is proposed. The differe
nce between the usual method and ours is pointed out. The dispersion r
elation of the pion meson including virtual particle-hole excitations
is analyzed. The results are compared numerically with that for the no
n-relativistic counterpart. The formulas of relativistic Delta-hole ex
citation induced by pion in nuclear matter are also discussed.