The molecular dynamics (MD) method is successfully applied to simulate the nitridation of titanium by the mixing technology with laser and plasma. Based on the simulation, the influence of the processing parameters, such as the laser power density and the scanning velocity on the effective thickness of the nitride layer, was investigated. It was found that, for each scanning velocity, there is a laser power density range within which the higher laser power density has the beneficial effect for nitriding treatment. Comparing the simulation and experimental results shows that the calculated results are in good qualitative agreement with the experimental results.