In this study, the relationship between fine roots, soil moisture, and soil organic carbon in artificial forests was analyzed. Three tree species, Robinia pseudoacacia, Platycladus orientalis, and Juglans regia were selected in the loess region of western Shanxi Province, China. Soil and root samples were taken from 0-500 cm depths to analyze the distribution pattern of fine root parameters, soil moisture content (SMC), and soil organic carbon density (SOCD). Soil moisture deficit (SMD) and organic carbon accumulation (SOCA) in artificial forests were evaluated with long-term cropland as a control. The results showed that:(1) the cumulative proportion of fine root biomass in shallow soil layers (0-70 cm) ranged from 56% to 71%, which showed obvious surface aggregation in all three forests. (2) The SMD in deep soil layers (70-500 cm) was significantly higher than that in shallow soil layers of all forests (P < 0.05). Compared with the control, the SMD in deep soil layers of artificial forests ranked as P. orientalis > J. regia > R. pseudoacacia. (3) The SOCD in deep soil layers accounted for 77%-86% of total soil profile SOCD across different forests. Compared with the control, the SOCA in P. orientalis and J. regia plots was generally positive, while the SOCA in R. pseudoacacia plot was negative. (4) The fine root parameters were positively correlated with both SMC and SOCD in shallow soil layers. However, in deep soil layers, the positive correlation was observed mainly with SOCD. The significant correlation with SMC was found only in R. pseudoacacia plot. The deep distribution of fine roots considerably differed among three artificial forests in the loess region of western Shanxi, which had an obvious influence on the deep SMC and SOCD distribution. Overall, the fine root distribution of R. pseudoacacia contributed to SMD while negatively affecting SOCA in the deep soil.