[Objective] The biological mechanisms underlying the effect of shrub forest development on soil in the Hobq Desert was analyzed in order to provide theoretical support for the establishment of a reasonable and effective desert shelter forest system. [Methods] Soil from 0—10, 10—20 cm, and 20—30 cm soil layers in a Salix psammophila forest system with different forest ages (6, 12, and 15 years) in the Hobq Desert was collected in early July 2023. The main physical and chemical properties and enzyme activities of the soil were analysed to reveal the mechanism of vegetation restoration on soil in this area. [Results] ① The fine particle content increased gradually with increasing forest age, whereas the soil bulk density and pH value decreased. ② Soil nutrients and enzyme activity levels clearly indicated surface aggregation in the vertical direction. There were significant differences in soil nutrients and enzyme activity levels among the different S. psammophila forest ages (p<0.05). The soil alkali-hydrolysable nitrogen, available phosphorus, available potassium, alkaline phosphatase activity, and catalase activity in the 12-year S. psammophila forest were 316.4%, 420.3%, 134.6%, 164.5%, and 94.8% higher than those of bare sand, respectively. Organic carbon, urease activity, and invertase activity under 15-year S. psammophila were 186.2%, 145.3%, and 2 703.4% higher than those of CK, respectively. ③ Soil enzyme activity was closely related to soil alkali-hydrolysable nitrogen, available phosphorus, available potassium, and organic carbon in different forest age restoration stages. [Conclusion] The establishment of the S. psammophila shelter forest in the Hobq Desert significantly improved soil nutrient levels and enzyme activity.