On the basis of one-dimensional fluid model, the characteristics of a homogeneous discharge at atmospheric pressure in nitrogen are numerically investigated. The primary processes of excitation and ionization in N2 are considered. The species included in the model are the electron e，N2 in the ground state，two ions N+2，N+4 and two metastable states N2(a1∑-u)，N2(A3∑+u). The simulation results show that the discharge in N2 appears mostly as a low-pressure Townsend discharge. The amplitude of discharge current is small and the gas voltage changes slowly in the breakdown phase. The electron density is much lower than that of ions and its maximum value occurs at the anode. Electrons are not trapped in the gas gap. There is no quasineutral plasma domain. The densities of metastable states N2(a1∑-u) and N2(A3∑+u) are at least three order higher than that of electron. The maximum metastable densities are located close to the anode, which determines the space structure of N2 discharge. Seed electrons needed in discharge are mainly provided by Penning ionizations between metastable molecules. This regime results in a low ionization level, which makes the discharge in N2 being close to a Townsend discharge. When changing discharge conditions properly, multiple-peak discharge can be obtained in N2.