A 35 d laboratory incubation experiment was conducted to study the effects of different fertilization treatments on nitrification and organic N mineralization in black soil under 25℃ and shallow flooding condition.The results showed that organic N mineralization and nitrification occurred normally under shallow flooding condition.In comparison with control,application of N fertilizer had no effect on nitrification and inhibited mineralization at the initial incubation period,while significantly increased nitrification and exerted no effect on mineralization at the later incubation period.The average net mineralization rate in the N fertilizer treatment was N 1.07 mg/（kg·d),which had no significant difference with the control.The average net nitrification rate was N 4.50 mg/(kg·d),which was 2.43 times of the control.Application of both N fertilizer and organic materials significantly promoted the immobilization of inorganic N in soil.The amount of N immobilized in the treatment of combined application of N fertilizer and straw was significantly higher than the treatment of combined application of N fertilizer and pig manure at the initial incubation period,the reverse was true at the later incubation period.For the treatment of combined application N fertilizer and straw,the average net mineralization rate was N -3.15 mg/(kg·d),which was significantly higher than the treatment of combined application N fertilizer and pig manure［N -5.61 mg/(kg·d)］.Under shallow flooding condition,application of N fertilizer plus organic materials significantly inhibited nitrification,the average net nitrification rates for the treatments of combined application of N fertilizer with pig manure and straw were N 0.29 and 0.18 mg/(kg·d),respectively,which were decreased by 93.5% and 960%,respectively,as compared with the treatment of N fertilizer application.