To gain a deeper understanding of the electron transport process and chemical reaction process in the plasma jet. A needle-ring plasma generator generated a stable plasma jet- at a discharge frequency of 10 kHz and an atmospheric pressure. The types of active particles, electron excitation temperature and plasma vibration temperature of atmospheric pressure argon/air plasma jet under different applied peak voltages were diagnosed by emission spectroscopy. The results show that the main active particles in the atmospheric pressure argon/air plasma jet are the second positive band system of N₂, Ar Ⅰ atoms and a small number of oxygen atoms, and the relative spectral intensity of the second positive band system of N₂ is the strongest and the most clear. The first negative band line of $N^{+}_{2}$ was not found in the emission spectrum of this experiment, which shows that there are almost no free electrons with electron energy higher than 18.76eV in the argon/air plasma jet. Plasma electron excitation temperature was calculated using5 spectral lines with a large difference in excitation energy of Ar Ⅰ atoms. The electron excitation temperature was between 7 000 and 11 000 K. With the increase of the applied peak voltage, the electron excitation temperature showed a trend of increasing first and then decreasing. The plasma vibration temperature was diagnosed by the second positive band system of N₂, and it was found that the vibration temperature of the atmospheric pressure argon/air plasma jet was between 3 000 and 4 500 K, which decreased with the increase of the applied peak voltage. This means that although the increase in peak voltage can effectively increase the kinetic energy of free electrons, when the electron kinetic energy is large, the interaction time between free electrons and nitrogen molecules will be shortened, and the collision energy transfer cross section between the two will be reduced. So the plasma vibration temperature shows a downward trend.