Finite-element models of the temperature coupled the concentration of kinetics during laser nitriding were considered. Coupled calculations of the non-steady state Fourier heat conduction equation and the Fick law of modified diffusion equation showed the variation and distribution of nitrogen concentration and the temperature in the metal surface layer. The results indicate that, the temperature of laser nitriding can be controlled exactly to gain the critical values of the heat flux and scanning rate respectively by trial-and-error, as the applicable reference range of progress. The modified diffusion equation, which considered the temperature gradient and thus showed a fairly good explanation of the N diffusion using the high-energy laser to fill the heat. The whole thickness of nitrides layer can be obtained through the simulation. The dynamic of laser nitriding is the high surface temperature gradient, which differs from the conventional process. The nitrogen concentration gradient is never considered as the main influence element. The thickness of nitrides increases when heat flux is increased or the scanning rate is reduced. Simulation indicates that good results can be obtained when these parameters are chosen properly.