To study the spatial distributions of soil nitrogen in stable sand dune, samples were collected at different depths (0-5, 5-10, 10-20 and 20-40 cm) from windward slope, top slope and leeward slope in the stable sand dune of Horqin Sandy land after the establishment of Caragana microphylla Lam for 25 years. The results showed that the contents of total N, NO3ˉ–N and NH4+–N decreased with the increase of soil layers. The differences of total N, NO3ˉ–N and NH4+–N from different slopes were significant (p＜0.01), and the differences under shrub soil were higher than under shrubs (p＜0.01). Nutrient contents at depth of 0-5 cm were higher than at other layers, which suggested more nitrogen was accumulated in surface layer as result of litter falling. The correlations between electrical conductivity and contents of total N, NO3ˉ–N and NH4+–N were positive significantly (p＜0.01), but the correlations between pH and the contents of NO3ˉ–N and NH4+–N were negative significantly (p＜0.01). Our results revealed that the enrichment of NO3ˉ–N and NH4+–N can decrease pH value. The establishment of Caragana microphylla plays an important role in improving sandy land soil.