The amount and distribution of residual mineral nitrogen plays a critical role in nitrogen supply for subsequent crops as well as nitrogen losses.A field experiment was carried out with the 15N-labelling technique to explore the effect of soil organic matter content on the residue of mineral fertilizer nitrogen in soil aggregates in a red paddy soil under the same nitrogen rate(150 kg/hm²).The results showed that compared with that in the low-organic matter soil，the proportion of macroaggregates(0.25～2 mm)was higher in medium- and high-organic matter soils，while the proportion of silt and clay(< 0.053 mm)was lower.The concentration of total nitrogen increased with increasing soil organic matter content in all aggregate sizes.Compared with the low-organic matter soil，the contents of total residual nitrogen in medium- and high-organic matter soils were significantly increased by 60.08% and 93.93% under the same nitrogen input，respectively. Compared with that in the low-organic matter soil，the content of residual nitrogen in the high-organic matter soil increased by 76.58%，108.32%，and 110.85% in macroaggregates，microaggregates(0.053～0.25 mm)，and silt and clay，respectively.Residual nitrogen was mainly located in macroaggregates(42.87%～46.81%).With the increasing of soil organic matter content，the proportion of residual nitrogen tended to decrease in soil macroaggregates，but tended to increase in silt and clay，albeit with no significant differences.Thus，improving soil fertility can not only increase the proportion of macroaggregates and enhance soil aggregation，but also contribute to the retention of residual mineral nitrogen and thus reduce nitrogen losses in the paddy soil.