This paper reports the results of the experimental study and chemical composition modeling for a DC nitrogen discharge burning above water cathode in the pressure range of 0.1-1 bar and at discharge current of 40 mA. The gas temperature, vibrational temperatures, reduced electric field strength, cathode voltage drop, and emission intensities of some nitrogen bands were obtained from experiment. The modeling chemical composition of plasma was carried out on the basis of these data. At modeling, the combined solution of Boltzmann equation for electrons, equations of vibrational kinetics for ground states of N-2, O-2, H2O and NO molecules, equations of chemical kinetics and plasma conductivity equation were used. The calculations agree with the measured bands intensities for the second positive system of N-2 and vibrational temperatures of . In the frame of the model proposed, the data of other studies were explained. The second kind collision of electrons with N-2 vibration excited states was shown to affect strongly the electron gas parameters. The electron average energy and electron density are given. The difference between the properties of the discharges in N-2 and air at the same conditions are discussed as well.