  We investigate in detail the chiral thermal transition of QCD in an improved
soft-wall AdS/QCD model with a simply modified 5D conformal mass of the bulk
scalar field. We also present a calculation in this model for the light meson
spectra and other low-energy characteristic quantities including the pion form
factor, the pi-rho coupling constant and the decay constants of pi, rho, a_1,
which are shown to result in a good agreement with experimental data except for
the pion decay constant. The thermal behavior of chiral condensate is studied.
It is found that such a simply improved soft-wall model incorporates the
crossover behavior of chiral thermal transition indicated by lattice
simulations. The expected chiral transition temperature can be obtained.
