Land use changes can affect soil nitrogen(N) transformation and greenhouse gas emission. Characterizing the distribution patterns of N-related microorganisms in different land uses along the soil profile provides significant information for understanding N cycling in ecosystems. Soil ammonia oxidation and denitrification play an important role in regulating nitrogen use efficiency, nitrate leaching and N₂O emission in soils. Ammonia oxidation, the conversion of ammonia to nitrite, is the critical step of nitrification and mainly performed by ammonia oxidizing archaea (AOA) and bacteria (AOB). The amoA gene has been used as a marker for both AOA and AOB for soil samples, while genes that encode key enzymes in nitrate reduction processes include nitrite reductase genes (nirS and nirK), nitrous oxide reductase gene (nosZ), and so on. Denitrification is a key process for controlling soil N availability and greatly influenced by land use change. However, the effect of land use conversion on the ammonia oxidization and denitrification are not well documented. This study aimed to investigate the spatial-temporal patterns of soil nitrification rate under different land-use types as well as the abundance of ammonia oxidizing microorganisms and denitrifiers using real-time PCR approach in spring and autumn. Soil samples were collected from maize land and woodland along the 0-100 cm soil depth in the suburban district of Beijing. Results showed that the potential ammonia oxidation (PAO), potential nitrite oxidation (PNO) rates, the abundance of N-related genes in maize land were significantly higher than those in woodland, which all showed a decreasing trend along the soil depth. Seasonal change had great impact on soil PNO, while no significant effects on PAO. The abundance of AOB amoA, denitrifiers nirS, nirK and nosZ I genes in spring was significantly higher than those in autumn, while AOA amoA abundance remained relatively stable across different seasons. The ratio of (nirS+nirK)/nosZ I reached the highest in the deep soil, indicating high capacity of denitrification. Correlation analysis found that soil organic matter, total N, ammonium and nitrate contents were positively correlated with the abundance of N-related genes. The relative contribution of specific N-related communities to soil nitrogen retention in soils merits further attention. In summary, the variation of ammonia oxidizing microorganisms and denitrifier abundance were closely related with soil available nitrogen contents and nitrification rates, which provides important information for soil nitrogen use and management in agricultural system. The performance of microorganisms in deep soil shed new light into understanding the denitrification process in the future studies.