The transition probabilities for the intercombination lines of 2s22p3s 3P1—2s22p21D2 and 2s22p3s 1P1—2s22p23P0,1,2 in NII have been calculated by using a large-scale multi-configuration Dirac-Fock method- In the calculation the most important effects of relativity, correlation, and relaxation are considered- The strong influence of correlation and relaxation effects on the transition probabilities have been confirmed by a compared calculation- When taking into account these effects in calculations, a remarkable improvement is found- From the results, the intensity of the 2s22p3s 3P1—2s22p21D2 line is supposed to be smaller than the previous theoretical prediction-