Soil microbial diversity and community life strategies are crucial for nutrient cycling during vegetation restoration. Although the changes in topsoil microbial communities during restoration have been extensively studied, the structure, life strategies, and function of microbial communities in the subsoil remain poorly understood, especially regarding their role in nutrient cycling during vegetation restoration. In this study, we conducted a comprehensive investigation of the changes in the soil microbial community, assembly process, life strategies, and nutrient cycling functional genes in soil profiles (0-100 cm) across a 36 year chronosequence (5, 15, 28, and 36 years) of fenced grassland and one grazing grassland on the Loess Plateau of China. Our results revealed that soil organic carbon increased by 76.0% in topsoil and 91.6% in subsoil after 36 years of restoration. The bacterial communities were influenced primarily by soil depth, while the fungal communities were highly sensitive to the years of restoration. Microbes in the subsoil recovered faster, and the microbial community structure and functional genes in the soil profiles gradually became more consistent following restoration. In addition, we observed a transition in microbial life history strategies from a persistent