For this experiment, a high-pressure magnetron sputtering plasma was used for plasma discharge with various flow rates of nitrogen gas. The introduction of nitrogen gas modifies the discharge leading to modifications of plasma parameters and ionization mechanism of transition species. The changes of relative emission for both neutral and ionic of argon were observed using optical spectrometer when the nitrogen gas is introduced into the discharged chamber. The relative intensities of both argon neutrals and ions were decreases as the flow rate of nitrogen gas increased. Optical emission spectroscopy (OES) was employed as non-invasive plasma diagnostics method and traced the light emission during plasma discharge. Furthermore, OES results were used in the calculation of rotational temperature by using formula was done for various discharge power. The results showed that the evaluated temperatures were almost the same as expected in conventional magnetron sputtering plasmas.