  The vortex-lattice melting transitions in two typical iron-based high-Tc
superconductor $Ba(Fe_{1-x}Co_{x})_{2}As_{2}$ (122-type)
and$Nd(O_{1-x}F_{x})FeAs$ (1111-type) for magnetic fields both parallel and
perpendicular to the anisotropy axis are studied within the elastic theory.
Using the parameters from experiments, the vortex-lattice melting lines in the
H-T diagram are located systematically by various groups of Lindemann numbers.
It is observed that the theoretical result for the vortex melting on
$Ba(Fe_{1-x}Co_{x})_{2}As_{2}$ for parallel fields agrees well the recent
experimental data. The future experimental results for the vortex melting can
be compared with the present theoretical prediction by tuning reasonable
Lindemann numbers.
