The cluster hexagon pattern was obtained in a dielectric barrier discharge in air/argon for the first time. Three plasma parameters, i.e. the molecular vibrational temperature, the molecular rotational temperature and the average electron energy of individual cluster in cluster hexagon pattern discharge, were studied by changing the air content. The molecular vibrational temperature and the molecular rotational temperature were calculated using the second positive band system of nitrogen molecules (Ｃ ３Πｕ→Ｂ ３Πｇ) and the first negative band system of nitrogen molecular ions (Ｂ ２Σ＋ｕ→Ｘ ２Σ＋ｇ). The relative intensities of the first negative system of nitrogen molecular ions (391.4 nm) and nitrogen molecules emission spectrum line (337.1nm) were analyzed for studying the variations of the electron energy. It was found that the three plasma parameters of individual cluster in cluster hexagon pattern increase with air content increasing from 16% to 24%.