Plasma enhanced ignition is an important way in the field of ignition auxiliary. It has got wide attention throughout the researchers both at home and abroad. Emission spectrum analysis is an important non-contact measurement method and could be used to analyze the parameters of the plasma. The coaxial corona discharge device was built and the emission spectrum was measured and analyzed. The physical model was constructed to calculate the vibrational temperature of nitrogen molecular. The results of the experiment and calculation results show that the emission spectrum of corona discharge is mainly second positive band system of nitrogen molecule. It is produced by the transition of the N2(C3Πu) and N2(B3Πu) which is the strongest and the most stable N2 emission spectrum. Ignore the emission spectrum of single line with no line width. The emission spectrum is mainly the N2(C-B,0-0), N2(C-B,1-3), N2(C-B,0-2), N2(C-B,1-4), N2(C-B,0-3) transition spectrum. The emission spectrum line of O2 is not obvious in the air corona discharge emission spectrum. The vibration temperature of nitrogen molecules was calculated according to the second positive band. The vibrational temperature of nitrogen molecules is 6193.21K, 3076.46K, 2788.61K at the discharge power of 1.325W, 4.272W, 8.4W. It laid a foundation of plasma enhance ignition for the further research.