[Objective] The hydrological process of litter mixed with soil in typical Robinia pseudoacacia mixed plantation was explored, in order to provide an important basis for improving the water conservation capacity of typical vegetation in the hilly area of the Loess Plateau. [Methods] We focused on five types of mixed artificial forests in Wuqi, Shaanxi (R. pseudoacacia×Pinus tabuliformis, R. pseudoacacia×Sophora viciifolia, R. pseudoacacia×Hippophae rhamnoides, R. pseudoacacia×Prunus persica, R. pseudoacacia×Armeniaca sibiric) and on pure Robinia pseudoacacia forests. We used a immersion method to determine the moisture content of soil that was mixed with different types and amounts of litter. We analyzed the evaporation process. [Results] ① The litter mixture in the vegetation plots was 204～2 087 g/m², the total average amount of litter in the soil was 733.53 g/m², and the average depth of the litter was 1.3～1.9 cm. ② The soil moisture of the six types of mixed plantations was ranked as follows: artificially mixed with litter soil > undisturbed mixed with litter soil > bare soil. The capillary water content of the pure R. pseudoacacia forest and R. pseudoacacia×S. viciifolia was significantly higher than in the other plots. ③ The overall trends in soil water evaporation when 700 g/m² litter was mixed with the soil in the six plantations were highly consistant: the soil water content decreased over time. The litter addition to the soil of the R. pseudoacacia×S. viciifolia and R. pseudoacacia×Armeniaca sibiric forests considerably increased the soil water content, whereas the soil water content of the soil mixed with litter in the R. pseudoacacia×H. rhamnoides forest slightly increased compared with the control. ④ The soil moisture content of the same forest type was higher than that of the unmixed soil after different amounts of litter were added. The maximum soil moisture contents of the pure R. pseudoacacia forest as well as R. pseudoacacia×Armeniaca sibiric and R. pseudoacacia×P. armeniaca forests were reached when the litter content was 1 000 g/m², and the maximum soil moisture content was reached in the R. pseudoacacia×H. rhamnoide forest when the litter content was 700 g/m². [Conclusion] Incorporating litter into the soil increased the soil moisture content, especially capillary moisture, and the effects of artificially added litter were more pronounced than those of naturally added litter. The type of forest also influenced the surface soil moisture levels. On the Loess Plateau, planting R. pseudoacacia×S. viciifolia and R. pseudoacacia×A. sibiric should be prioritized to increase water conservation in the region.