Soil biologically based phosphorus plays a vital role in improving forest productivity and in biogeochemical cycles. It is very important to study the effects of different forest restoration pathways on soil biologically based phosphorus for the adaptive restoration and sustainable management of the degraded forests. In this study, we determined the soil biologically based phosphorus (CaCl₂-P, Citrate-P, Enzyme-P, and HCl-P) under three restoration pathways of subalpine forests, i.e., Picea asperata plantation forest (artificial planting, PF), Abies faxoniana-Betula albosinensis natural secondary forest (natural without assisted regeneration, NF), and P. asperata/mixed broadleaf forest (natural regeneration after artificial planting, MF), in western Sichuan by using biologically based phosphorus (BBP) method. The results showed that different forest restoration pathways had significant effects on soil biologically based phosphorus (P<0.05). Soil Citrate-P and Enzyme-P of NF and MF were significantly higher than those of PF (P<0.05), while soil HCl-P of PF was significantly higher than that of NF (P<0.05). The natural regeneration is the best way for improving soil biologically based phosphorus among the three forest restoration pathways in subalpine of western Sichuan. The four soil biologically based phosphorus fractions under the three forest restoration pathways showed significantly positive correlation with soil available phosphorus, and the correlations between soil available phosphorus and biologically based phosphorus (except CaCl₂-P) in NF were stronger. The soil physicochemical properties, including total potassium content, ammonium nitrogen, and pH value, significantly affected soil biologically based phosphorus in NF with the highest degree of interpretation by total potassium content (r²=0.63, P=0.001). Soil pH value, calcium content and soluble organic carbon content were the main soil physicochemical properties that significantly affected soil biologically based phosphorus in MF (P<0.05). Soil physicochemical properties that had significant impacts on soil biologically based phosphorus in PF were the content of soil organic carbon, iron, and soluble organic carbon. The interpretation rate of soil physicochemical properties to forest soil biologically based phosphorus under the three restoration pathways exceeded 80%. The effect of forest restoration pathways on soil biologically based phosphorus is related to soil physicochemical properties.