The purpose of the present work consists in the elaboration of numerical computing program allowing the simulation of various species behaviour present in plasma reactor during films formation by cold plasma in DC glow discharge. After application of some simplifying hypotheses, we have developed a simulation model based on a fluid approximation. The elaborated model was based on finite differences method solved by MATLAB software. We applied the model to simulate the plasma in the case of atomic gases (Ar) and molecular (CH4) gases. The simulation results are given in terms of spatial distribution of charge densities, electric potential and electric field between electrodes space. The effect of some discharge parameters such as the pressure, and the density of the gas was also investigated.