  It is shown that in supersymmetric models (SUSYMs) the large supersymmetric
contributions to $B \to X_s{\mu}^{+}{\mu}^{-}$ come from the Feynman diagrams
which consist of exchanging neutral Higgs bosons (NHBs) and the chargino-stop
loop and are proportional to $m_b m_{\mu}$tan$^3\beta/m_{h}^2$ when tan$\beta$
is large and the mass of the lightest neutral Higgs boson m$_h$ is not too
large (say, less than 150 Gev). Numerical results show that the branching
ratios of $B \to X_s{\mu}^{+}{\mu}^{-}$ can be enhanced by more than 100%
compared to the standard model (SM) and the backward-forward asymmetry of
lepton is significantly different from that in SM when tan$\beta \geq 30$.
