Abstract: Taking one-year-old Tsoongiodendron odorum seedlings as experimental object, using a completely random design, setting 3 biochar concentrations and 2 aluminum concentrations, the effects of biochar on the growth physiological characteristics of the T. odorum seedlings under aluminum stress were studied. The results showed that in the aspect of growth, when the same amount of biochar was applied, the growth indexes of the T. odorum seedlings were reduced under aluminum stress; when aluminum stress was not applied, biochar could promote the growth of seedlings; under aluminum stress, biochar could effectively alleviate aluminum stress and promote the growth of seedlings, and 8 g biochar increased the most. In physiology, when the same amount of biochar was applied, malondialdehyde(MDA), free proline content and aluminum content in roots, stems and leaves of T. odorum seedlings increased under aluminum stress, however, the content of soluble sugar, soluble protein and chlorophyll decreased, applying biochar could effectively improve the content of soluble sugar, soluble protein and chlorophyll, and the content of MDA, free proline and aluminum content in roots, stems and leaves decreased. It could effectively alleviate the damage caused by aluminum stress on the resistance physiology and photosynthetic pigment of T. odorum seedlings, and it was also the best when 8 g biochar was applied. In conclusion, application of biochar can promote the growth of T. odorum seedlings, and effectively alleviate the damage of aluminum stress on growth, photosynthetic pigment and resistance physiology, improve the aluminum resistance of T. odorum seedlings, when 8 g biochar is applied, the effect of alleviating aluminum stress is the best.