  We propose the Schwinger-Dyson (SD) formalism based on lattice QCD, i.e.,
LQCD-based SD formalism, for the study of dynamical chiral-symmetry breaking in
QCD. We extract the kernel function K(p^2) in the SD equation from the lattice
data of the quark propagator in the Landau gauge. As remarkable features, we
find infrared vanishing and intermediate enhancement of the kernel function
K(p^2) in the SD equation. We apply the LQCD-based SD equation to thermal QCD,
and calculate the quark mass function at the finite temperature. We find chiral
symmetry restoration at the critical temperature T_c \sim 100MeV.
