  We investigate the spin correlations in top quark pair production near
threshold at the $ e^- e^+ $ linear collider. Comparing with the results above
the threshold region, we find that near the threshold region the off-diagonal
basis, the optimized decomposition of the top quark spins above the threshold
region, does not exist, and the beamline basis is the optimal basis, in which
there are the dominant spin components: the up-down (UD) component for $e_L^-
e^+$ scattering and the down-up (DU) component for $e_R^- e^+$ scattering can
make up more than 50% of the total cross section, respectively.
