In order to study the influence of stand density on soil infiltration performance, five kinds of Robinia pseudoacacia Linn. stands (1 075, 1 300, 1 575, 1 800, 2 150 trees/hm²) in Loess region of Western Shanxi Province were selected as the research object. The soil infiltration process was determined by double-loop infiltration method, and the correlation of infiltration characteristic index and soil physicochemical properties were also analyzed. The results showed that: (1) The process of soil infiltration in Robinia pseudoacacia Linn. with different densities was the same, all of them went through the stages of transient infiltration, gradual infiltration, and stable infiltration. (2) There were significant differences in initial infiltration rates, stable infiltration rates, average infiltration rates and cumulative infiltration amount under different stand densities (P<0.05). With the increase of stand densities (1 075~1 800 trees/hm²), soil infiltration capability increased. After the stand density of Robinia pseudoacacia Linn. was more than 1 800 trees/hm², there was a trend of weakening in soil infiltration. Therefore, it was suggested that the management density of Robinia pseudoacacia Linn. in Loess region of Western Shanxi Province should be 1 800 trees/hm². (3) The soil infiltration process of Robinia pseudoacacia Linn. with different densities was simulated by Kostiakov model, Horton model, Philip model and Universal Empirical model. In terms of R², the Universal Empirical model had the largest R²(0.990), and could be used as a predictive model for the soil infiltration process of Robinia pseudoacacia Linn. in Loess region of Western Shanxi Province. (4) Soil infiltration capability was negatively correlated with soil bulk density (P<0.01), positively correlated with organic matter and > 0.25 mm water-stable aggregate (P<0.01), and positively correlated with pore condition and water content.