  Based on the infrared improved soft-wall AdS/QCD model which can lead to a
consistent prediction for the mass spectra of light resonance mesons, we extend
it to the finite temperature system and carry out the calculation for the quark
number susceptibility with finite quark mass. As a consequence, we show that
the quark number susceptibility grows rapidly with a continuous blow-up in a
narrow temperature interval as the temperature increases, and there is a peak
when the temperature is around $T \simeq 160 \sim 190$ MeV depending slightly
on the models, the resulting critical temperature is about 170MeV, which agrees
remarkably with the lattice QCD calculation.
