Dielectric barrier discharge (DBD) at atmospheric pressure has many advantages such as multi-category, depth and breadth, normality, etc. In this paper, a series of parameter diagnoses for the coaxial electrode discharge test were carried out. Argon ionization experiments were carried out under the conditions of 11.4 kHz discharge frequency and 5.4～13.4 kV (interval 1 kV) discharge peak voltage by using self-developed DBD combustion actuator at standard atmospheric pressure. Atomic emission spectrometry (AES) was employed to test and analyze argon plasma excitation and spectroscopy; two-line method and Boltzmannmethod were employed to test electron excitation temperature; electronic density was calculated according to Stark broaden law; the variations in electron excitation temperature and electron density with the increase of the peak discharge voltage were obtained. The results showed that the electron excitation temperature does not monotonically increase with the increase of applied voltage, which indicates the main characteristics of the micro-discharge are not dependent on the external voltage strength, but on the gas composition, gas pressure and discharge model; Increasing discharge power could only increase micro-discharge number; the maximum electron excitation temperature is up to 3 500 K; the electron density which achieves 108～109 cm3 tends to be a quasi linear trend with the increase of applied voltage. The degree of ionization is weak. The exploration of these parameters is of great significance to the study of plasma.