  We study the exclusive decays of $B\to K^{(*)}\ell^+ \ell^-$ by the results
in the perturbative QCD with the heavy quark effective theory and lattice
calculations. We obtain the form factors for the $B\to K^{(*)}$ transitions in
the whole allowed region. Our predictions on the branching ratios of $B\to K
\ell^{+} \ell^{-}$, $B\to K^{*} e^{+}e^{-}$, and $B\to K^{*} \mu^{+} \mu^{-}$
are $0.53\pm 0.05 ^{+0.10}_{-0.07}$, $1.68\pm 0.17^{+0.14}_{-0.09}$, and
$1.34\pm 0.13 ^{+0.11}_{-0.06}\times 10^{-6}$, where the errors are from the
quark mixing elements and hadronic effects, respectively. We also find that our
definitions of the T-odd observable and the up-down asymmetry of the $K$ meson
in $B\to K^*\ell^+ \ell^-\to K\pi\ell^+ \ell^-$ can be used to probe new
physics.
