[Objective] To explore the effects of Robinia psedudoacia plantations on the soil moisture and nutrient characteristics, in order to provide theoretical basis for vegetation restoration and ecological reconstruction in semiarid loess hilly region.[Methods] Based on data collected from soil sampling in the field and laboratory measurement, the soil moisture and nutrient characteristics under different R. psedudoacia plantations with various ages were analyzed in the loess hilly region of western Shanxi Province.[Results] R. psedudoacia plantanations effectively improved soil moisture conditions, especially in the early stages of the planting. The average content of soil organic content and total nitrogen increased significantly, and showed an apparent surface aggregation. Surface soil moisture and nutrient conditions were better than that of the underlying soil layers after R. psedudoacia restoration. Soil moisture inside the pits above 40 cm was 3.97% higher than that outside the pits, and 2.74% higher in soil below 40 cm. Soil organic content, total nitrogen, total phosphorus and total potassium inside the pits was increased by 6.61%, 6.14%, 1.55% and 1.98% respectively, than those outside the pit at 0-20 cm soil layer, while there were no significant improvements for the total phosphorus and the total potassium content below 20 cm soil layer.[Conclusion] R. psedudoacia plantanations has improved moisture and nutrients conditions in surface soil layers.