In this study, according to the main types of artificial afforestation and natural enclosure vegetation restoration in Wuqi county in a typical loess hilly region of northern Shaanxi, samples of Hippophae reamnoides and Prunus armeniaca forests and natural restoration grassland under different cropping years after 5, 15, and 40 years were selected and sampled to determine soil profiles. The fine root biomass and soil physicochemical properties were analyzed, and variations in the regularity and coupling relationships between samples were evaluated under different restoration types and at different years. The results were as follows:(1) In general, the fine root biomass of abandoned grassland and P. armeniaca forests increased with an increase in the number of abandoned years and stand age. The fine root biomass of artificial tree species was larger than that of natural restoration grassland, and the biomass showed a decreasing exponential law with increasing depth. (2) The soil water content of the grassland ecosystem was significantly higher than that of artificial P. armeniaca and H. reamnoides forests. The stability of soil aggregates increased both under artificial afforestation and natural enclosure vegetation coverage, and the content of organic matter, total nitrogen, and total phosphorus were also improved. The soil average water content was reduced with the increase in abandoned years. (3) Fine root biomass showed an obvious correlation with soil bulk density and agglomerate stability, and fine roots played an important role in soil structure improvement.