In this research, the plasma parameters were determined each of electron temperature (Te), electron density (ne), plasma frequency (fp), Debye length (λD). The plasma jet operates with argon gas at atmospheric pressure. It is equipped with an alternating AC high voltage power supply of 12 kilovolts and a frequency of 20 kilohertz. Plasma parameters were calculated from the emission spectrum using an optical emission spectrometer (OES) which captured the spectrum resulting from the plasma at various flow rates of argon gas from 0.5 to 5 L/min. Several peaks of argon gas (ArI) and nitrogen gas (N2) were appeared, where the results showed that the highest peak of argon gas was at 763.51 nm for the fifth flow of argon gas. The results indicated the electron temperature (Te) decrease with increased flow rate and ranged (1.296–0.645) ev, while the electron density (ne) increased with flow rate and ranged were (4.054-5.068x1017) cm-3, respectively. In contrast an increase in the intensity of spectral lines was observed.