The emission spectra of pure oxygen in dielectric barrier discharge at atmo spheric pressure were observed. Comparison between experimental and fittings pectra of oxygen A band (ｂ １Σ＋ｇ→Ｘ ３Σ-ｇ)(0,0)was used to determine the gas temperature,and the electronic temperature was calculated from O Ⅰ lines. The causation of oxygen A band in atmospheric dielectric barrier discharge was discussed by means of analysis of producing and quenching approaches. The result showed that the electronic temperature,(11 800±400) K,was much higher than the gas temperature,(650±20) K. The emission from ａ １Δｇ or Ａ ３Σ＋ｕ was not been observed,but atmospheric band with its resoluble rotational structure was measured.