【Objective】Enchytraeus crypticus is a model species widely used in toxicology studies and soil environmental risk assessments. It is known for its low sensitivity to polycyclic aromatic hydrocarbons (PAHs) which are prevalent soil contaminants. However, there remains a lack of toxicokinetic research on this species. This study selected phenanthrene as a representative PAH to investigate its toxicokinetics on E. crypticus under different exposure concentrations. 【Method】Laboratory experiments were conducted to study the toxicokinetics of phenanthrene on E. crypticus at three concentrations: 20, 40, and 80 mg·kg-1. Phenanthrene uptake and elimination were monitored over time. Toxicokinetic modeling was used to calculate the uptake rate constant, elimination rate constant, and bioaccumulation factor (BAF). A comprehensive model was also fitted to assess the overall phenanthrene dynamics. 【Result】The results indicated that phenanthrene rapidly accumulated in E. crypticus during the initial exposure phase and reached steady-state concentrations of 47.83±11.69, 106.8±15.52, and 364.1±51.11 mg·kg-1 at exposure levels of 20, 40, and 80 mg·kg-1, respectively. During the elimination phase, phenanthrene was eliminated at a decreasing rate over time. The uptake rate constants increased significantly with exposure concentration, while the elimination rate constants declined, resulting in elevated BAF values at higher concentrations. E. crypticus exhibited high tolerance and bioaccumulation potential for phenanthrene, with prolonged retention at high exposure levels, posing potential risks to soil ecosystems. 【Conclusion】The study concludes that the concentration-dependent toxicokinetics of phenanthrene, particularly differences in uptake, accumulation, and elimination, could result in varied soil environmental risk assessments. These findings underscore the need for careful consideration of such concentration-dependent dynamics in PAH risk evaluations. Furthermore, low-sensitivity species like E. crypticus should receive special attention in environmental risk assessments to ensure accurate evaluations of PAH-related risks.