Returning farmland to forests is an important ecological initiative in China. The establishment of a soil health evaluation system to evaluate soil health in farmlands returned to forests under different vegetation restoration practices in the black soil region of Northeast China can provide data support for the scientifically sound evaluation of the ecological benefits of returning farmland to forests. Surface soils under two major vegetation types (pure birch forest and elm-lonicera mixed forest) in the black soil region of Northeast China were used as the objects of study, and cultivated land was used as the control. In the 0–10 cm soil layer, the soil health scores were in the order mixed forest (11.80 points) > pure forest (8.80 points) > CK (5.47 points). In the 10–20 cm soil layer, the soil health scores were in the order mixed forest (8.41 points) > pure forest (7.03 points) > CK (4.03 points). The soil health scores of the pure and mixed forests were significantly higher than those of the control, and the soil health scores of the mixed forest were the highest. The effect of vegetation on the restoration of topsoil was more significant after return of farmland to forest. Vegetation improved soil health mainly by increasing the stability of soil structure. These findings suggest that plant species can be enriched to restore degraded soils and that mixed forests can be used to improve soil health.