Aggregates, as the basic structural unit of soil, contribute differently to soil total nitrogen (TN) stocks in terms of TN content at each grain level. Above-ground vegetation in the process of grassland restoration will affect the composition of soil aggregates and the distribution of TN at each grain level, which will certainly have an impact on the stability of aggregates and soil nitrogen accumulation. Therefore, this study investigated the patterns of nitrogen accumulation in soil aggregates during the restoration of grassland by restoring 10 a, 20 a, 30 a, 40 a, and 50 a grassland and control farmland (CK). The results are as follows. 1) During the 50 a restoration process, the grass community underwent the succession process of Artemisia inchiensis→Artemisia inchiensis+Artemisia ferruginea→Artemisia ferruginea+Lespedeza davurica→Artemisia ferruginea+Stipa bungeanaTrin→Artemisia ferruginea+Bothriochloa ischaemum. The species diversity index of the grass community showed a trend of increasing and then decreasing with the increase of restoration years and the carbon and nitrogen contents of aboveground plants, roots, and litter showed a trend of increasing and then decreasing. 2) Soil pH and bulk density showed a decreasing trend during the restoration of grassland, while soil water content showed a decreasing and then increasing trend. The soil organic carbon content increased significantly during the restoration process (P<0.05). The soil TN content showed an increasing and then decreasing trend with the restoration years, while TN storage increased year by year. The restoration of 10-50 a grassland increased by 8.10%-118.92% compared with CK. 3) The percentage of soil microaggregates (0.053-0.25 mm) in grassland communities with different restoration years was the largest, which showed a decreasing trend with the increase of restoration years. However, the percentage of large aggregates (>2 mm) and medium aggregates (0.25-2.00 mm), the mean weight diameter (MWD), and geometric mean diameter (GMD) showed an increasing trend. 4) The TN content of medium aggregates was the highest in the grass community at different restoration years and the TN content of each grain level aggregates showed a decreasing and then increasing trend with the restoration years. The TN stocks of microaggregates were the highest in the grass community, the TN stocks of large and medium aggregates showed an increasing trend with the increase of restoration years, and the TN stocks of micro and silt+clay fractions aggregates (<0.053 mm) fluctuated with the increase of restoration years. The TN stocks of each grain level aggregates were significantly correlated with the biomass of above-ground plants, roots and litter as well as carbon and nitrogen content (P<0.05). 5) The contribution of large aggregates to soil TN stocks during grassland restoration was 70%, and the increase in the percentage of large aggregates was the main reason for the high contribution of large aggregates. In conclusion, grassland restoration is beneficial to soil stability as well as nitrogen accumulation.