  We study the scalar and pseudoscalar condensations and the eta^prime meson
correlators of the two-flavor massive Schwinger model in the non-zero theta
vacuum. Exploiting our new method which was developed to investigate
topological effects in the previous work, we find that the pseudoscalar
condensation is non-zero and there exists a long-range correlation of the
eta^prime meson. This phenomenon is well described by the clustering property.
We also find that even in theta=0 case the cancellation of the long-range
correlation is nontrivial and requires accurate contributions from higher
topological sectors. Our results imply that the fluctuation of the
``disconnected'' diagram originates from the pseudoscalar condensation in each
topological sector.
