【Objective】Afforestation is the main measure for desertification combating and plays a key role in improving soil quality and reestablishing degraded ecosystem functions. However, the spatial distribution in soil chemical properties and bacterial communities after the forest reconstruction in sandy land has not been well evaluated. The objective of this study was to investigate responses of the soil chemical properties and bacterial communities in soil profiles to afforestation and to provide a scientific basis for the healthy management and fertility cultivation of barren sandy soils in Northern China. 【Method】In this study, we selected Pinus sylvestris var. mongolica plantations which included 0, 5, 8, and 15 by using the space-time substitution method in Mu Us Sandy Land located in Yulin, Shannxi, China. Soil samples were collected from 0-10 cm, 10-20 cm, 20-30 cm, 30-60 cm, and 60-100 cm. The high-throughput amplicon sequencing of the 16S rRNA and Functional Annotation of Prokaryotic Taxa (FAPROTAX) tool was used to quantify the composition, diversity, and putative ecological functions of soil bacterial community, and then to determine the relationship between bacterial community and soil properties. 【Result】Results showed that: (1) The conversion from sandy land to plantations increased soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents, but decreased available nitrogen (AN), available phosphorus (AP) contents, and pH. TN content decreased with soil layers, while AP and pH were increased. TP had no significant change in soil profiles. (2) Afforestation significantly changed the relative abundance of the Proteobacteria, Acidobacteria and Chloroflexi, and increased soil bacterial ACE(abundance-based coverage estimator) index. Importantly, the vertical spatial variation in bacterial communities decreased. (3) FAPROTAX showed that after 15 years of afforestation, cellulolysis and aromatic compound degradation decreased by 54.65% and 72.18%, respectively. However, nitrogen fixation and denitrification were enhanced by 99.26% and 100.5%, respectively. (4) Redundancy analysis and Pearson correlation analysis indicated that SOC and pH were the key factors varying the bacterial community and putative ecological functions. 【Conclusion】Overall, the conversion from sandy land to Pinus sylvestris var. mongolica plantations can negatively affect soil available nutrients such as AN and AP, and also alter the diversity and putative functions of the soil bacterial community. Consequently, artificial control measures (such as regulation of litter degradation and nutrient return) are crucial for improving the bioavailability of nutrient elements and microbial functional diversity in arid and barren sandy soil. In the future, on-the-spot preservation and decomposition of litter in the ecological restoration work of artificial forests in sandy areas should be prioritized.