  The halo spin-spin correlation function, $\eta(r)$, measures how rapidly the
strength of the alignments of the spin directions between the neighbor halos
change with the separation distance, $r$. The previous model based on the tidal
torque theory expresses the halo spin-spin correlation function as a power of
the linear density two-point correlation function, $\eta(r)\propto \xi^{n}(r)$,
predicting $n=2$ in the linear regime and $n=1$ in the non-linear regime. Using
a high-resolution N-body simulation, we show that the halo spin-spin
correlation function in fact drops much less rapidly with $r$ than the
prediction of the previous model, finding $\eta(r)$ to be statistically
significant even at $r\ge 10\,h^{-1}$Mpc on the dwarf galaxy scale. Claiming
that the anisotropic tidal effect is responsible for the failure of the
previous model, we propose a new formula for the halo spin-spin correlation
function expressed in terms of the integrals of $\xi(r)$. The new formula with
the best-fit parameters turns out to agree excellently with the numerical
results in a broad mass range, $0.05\le M/(10^{11}\,h^{-1}\,M_{\odot})\le 50$,
describing well the large-scale tail of $\eta(r)$. We discuss a possibility of
using the large-scale spin-spin correlations of the dwarf galactic halos as a
complementary probe of dark matter.
