Soil organic nitrogen mineralization is one of the important indexes of soil nitrogen fertility and a crucial factor affecting crop yield.The dynamic characteristics of soil nitrogen accumulation and mineralization in red soil-derived double cropping paddy fields were systematically studied based on 33 years of long-term fertilization experiment.The experiment began in 1984，and five fertilization treatments were selected:CK(no fertilizer)，NPK(application of chemical fertilizer)，50F+50M(50% NPK plus 50% organic fertilizer)，30F+70M(30% NPK plus 70% organic fertilizer)and 70F+30M(70% NPK plus 30% organic fertilizer).Topsoil samples(0～20 cm)were collected before early rice planting in 2017.The amount and rate of soil nitrogen mineralization were determined by waterlogged incubation intermittent leaching method.First-order kinetic model was used to fit soil nitrogen mineralization potential(N0)and mineralization rate constant(k)，ect.The results showed that long-term fertilization significantly increased the content of organic carbon，total nitrogen and alkali-hydrolyzed nitrogen，and the most effective treatment was combined application of organic and inorganic fertilizers，and increased with the increase of organic fertilizer input.30F+70M treatment significantly increased the contents of ammonium nitrogen，nitrate nitrogen and total mineral nitrogen，which were 47.0%，64.6% and 49.7% higher than NPK，respectively.The soil net mineralization rate and mineralized nitrogen release were significantly increased by 33 a continuous fertilization，ranking as 30F+70M > 50F+50M > 70F+30M > NPK > CK，and the organic plus chemical fertilizations was 2.70 and 1.41 times higher than that of chemical fertilizer on average.Long-term fertilization significantly increased the mineralization potential of soil nitrogen by 65.9%～196.0%.70F+30M treatment significantly increased N0 and reduced k of paddy soil compared with NPK.Soil organic matter，total nitrogen，alkali-hydrolyzed nitrogen and ammonium nitrogen significantly affected N0，N0/N，cumulative mineralization amount and mineralization rate of nitrogen，and the soil nitrogen mineralization rate constant(k)showed a very significantly negative correlation with C/N.Long-term combined application of chemical nitrogen fertilizer and low proportion organic fertilizer leads to the slow and lasting nitrogen supply of paddy soil，and can continuously supplement nitrogen during the growth and development of rice.