To study the nitrogen fixation reaction path in micro-channel gas-liquid two-phase dielectric barrier discharge (DBD), we propose a method to determine DBD characteristics using emission spectra. Based on the experimental results obtained for gas-liquid two-phase DBD nitrogen fixation, the characteristic parameters and active particle composition of DBD plasma are derived using the measured emission spectra, facilitating an in-depth analysis of the DBD nitrogen fixation reaction path. The experimental results indicate that the proposed method can accurately determine the vibration temperature, rotation temperature, and active particle composition of N₂ during the DBD nitrogen fixation reaction. This approach circumvents the plausible effects of traditional intrusive measurement methods on the nitrogen fixation reaction of DBD. Therefore, this study offers a novel, reliable, and practical method for investigating the gas-liquid two-phase DBD nitrogen fixation reaction path.