[Objective] The changes of root exudates of Koelreuteria paniculata and Cinnamomum camphora under phenanthrene(PHE) were analyzed in order to provide scientific basis for screening tree species resistant to polycyclic aromatic hydrocarbons pollution and further phytoremediation of polycyclic aromatic hydrocarbons pollution.[Methods] Three concentrations of phenanthrene[L₀(CK, 0 mg/kg), L₁(100 mg/kg), L₂(1 000 mg/kg)] were set up in this experiment. Total organic carbon(TOC), total carbon(TC), total nitrogen(TN) and root activity in root exudates of Koelreuteria paniculata and Cinnamomum camphora trees were determined by pot experiment.[Results] ① With the increase of phenanthrene concentration, the contents of TOC and TC in root exudation of Koelreuteria paniculata and Cinnamomum camphora decreased, while the contents of TN increased first and then decreased with the increase of phenanthrene concentration; ② With the increase of phenanthrene concentration, the total absorption area and active absorption area of roots of Koelreuteria paniculata and Cinnamomum camphora showed a downward trend. ③ Under the three treatments, the contents of TC, TOC and TN in root exudates of Koelreuteria paniculata were higher than those of Cinnamomum camphora, and the total and active absorption areas of Koelreuteria paniculata root were also higher than those of Cinnamomum camphora.[Conclusion] By comparing root exudation and root activity of Koelreuteria paniculata and Cinnamomum camphora under phenanthrene stress, it showed that Koelreuteria paniculata had better tolerance to phenanthrene than Cinnamomum camphora.