The Ising model with Fe
4N structure was studied within the mean-field theory. The theoretic expressions of magnetization and free energy in the nearest neighbor interaction system were deduced. The magnetization curves and phase diagrams were given at a fixed value of through numerical calculation, and the phase transition characteristics were obtained. It was found that the second-order phase transitions were general phenomena, and the first order-order, the first order-disorder phase transitions and reentrant phenomena only exist in a certain range of crystal field. In the phase diagram the curves of reentrant phenomena, the first order-order and the first order-disorder phase transitions intersect at one point. It was found that the phase transition characteristics in the phase diagram at low temperature are completely consistent with the characteristics in the ground-state phase diagram.