Large proportion of available nitrogen in soil is produced by mineralization, which can be changed by tillage management. However, tillage effects on soil N supply in cropping systems remain unclear. This study addressed dynamics of nitrogen mineralization within soil aggregates of a subtropical purple soil under two different tillage: conventional tillage (CT) and combination of ridge with no-tillage (RNT). Soil samples were separated into large aggregates (> 2.0 mm), macro-aggregates (2.0 - 0.25 mm), micro-aggregates (0.25 - 0.053 mm) and silt + clay fractions (< 0.053 mm) by wet-sieving method. Regression analysis showed that the time-dependent kinetics of net nitrification were best fitted with a first-order model for soil aggregates and whole soil, but net nitrification rate within different aggregate sizes were found significantly different. Similar patterns of net nitrification rate changes with the time were found in aggregates under CT and RNT. The highest mineralization potential (Np) was observed for 2.0 - 0.25 mm fraction and the lowest for >2.0 mm fraction, regardless of tillage regime. Potential mineralization rate (Vp) and actual average net mineralization rate (Va) associated with macro-aggregates (2.0-0.25 mm) were significantly higher than other sizes of aggregates and whole soil. For whole soil, CT regime, in comparison to RNT, increased Np by 33.9%, but the kinetics model of nitrification was not affected by tillage. This inferred that although nitrogen mineralization could be stimulated in no-tillage, mineralization associated with aggregates was not altered by tillage.