In order to explain the resource allocation characteristics of plant leaves and their adaptation strategies with soil factors, the study carried out in a pure plantation of Pinus tabuliformis and Pinus sylvestris and a mixed forest of Caragana korshinskii in Xinrong District, Datong City, Shanxi Province, on the northeastern edge of the Loess Plateau, using the sample method to collect branches in the four directions of east, west, north and south from the well-grown whorls in the middle of the canopy of the sample trees, and to select representative annual and perennial leaves at three locations on each branch: inside, middle and outside; nine sampling points were selected in each sample square using the “S” sampling method. The soil samples were collected by soil auger from 0 to 20 cm at each site; the functional characteristics, soil physical and chemical properties and the relationship between the two were determined and analysed under different silvicultural patterns of P. tabuliformis and P. sylvestris. The results showed that: (1) the differences in leaf functional traits between different afforestation modes of P. tabuliformis and P. sylvestris were concentrated between stoichiometry; as leaf age increased, P. tabuliformis and P. sylvestris both showed an increase in dry matter content and a decrease in N and P contents. (2) Soil total P and total N contents were the main explanatory factors for current year and perennial leaves of P. tabuliformis, respectively. Soil total P was significantly and positively correlated with current year leaf C∶N ratio, organic C and C∶P ratio, and negatively correlated with total N, leaf area and leaf dry matter content, while soil total N was positively correlated with perennial leaf total P content, and negatively correlated with leaf organic C, C∶P ratio and C∶N ratio. (3) The key soil factors for the functional traits of annual leaves of P. sylvestris were soil bulk and total P content, which were positively correlated with the ratio of leaf C, N and P, dry matter content and C content, and negatively correlated with N and P contents; the key soil factors for the functional traits of perennial leaves were soil bulk, water content and pH, which were positively correlated with leaf N and P contents, and negatively correlated with C content, dry matter content and specific leaf area, etc. (4) Leaf functional traits in pure stands of P. tabuliformis and P. sylvestris were more likely to be shifted towards higher levels of key soil factors, suggesting that the mixture with Caragana korshinskii can effectively differentiate the concentrated demand for key soil factors for leaf growth. However, the growth of the stands was weakened in the mixed afforestation mode, which was combined with the lack of resources in the study area and the high planting density of the stands, and the competition increased the survival pressure resulting in the restricted growth of the stands.