In the present study, dielectric barrier homogenous discharge in nitrogen was obtained between large plate electrodes (150×300 mm) at atmospheric pressure and the emission spectra of N2(C3Πu→B3Πg) and N+2(B2Σ+u→X2Σ+g 0-0 391.4 nm) were recorded. It was found that both the emission intensities of N2(C3Πu→B3Πg) and N+2(B2Σ+u→X2Σ+g 0-0 391.4 nm) increase with the rising of the applied voltage and the driving frequency, respectively. The main physicochemical formation mechanism of N+2(B2Σ+u) in N2 and He+N2 mixtures homogenous discharge was discussed, and the penning ionization was proved to be the dominant formation mechanism.