On the basis of full relativistic theory, transition probabilities of 2p4f—2p3d for NⅡ have been calculated using multi-configuration Dirac-Fock method. The results are well consistent with experimental value. In the present work, the influence of relativistic effects, electron correlation, relaxation effects, Breit interaction and quantum electrodynamic effects on fine structure and transition probabilities are investigated in detail. The results show that the relativistic effects, electron correlation and relaxation effects are important to the calculations of energy structure and transition probabilities.