Abstract: In order to investigate the disposal of low concentration ammonia-nitrogen wastewater (concentration less than or equal to 50 mg/L) using a functional composite, a new photocatalyst, TiO₂/biochar composite, was prepared by immobilizing TiO₂ nanoparticles onto biochar synthesized by the hydrothermal method. The properties of the as-prepared TiO₂/biochar were further characterized by X-ray diffraction, scanning electron microscopy, and UV-Vis diffuse reflectance spectroscopy. The photocatalytic degradation of ammonia-nitrogen from water was evaluated along the gradients of load ratio, pH, temperature and initial concentrations of ammonia-nitrogen. The results showed that TiO₂ nanoparticles were well dispersed on the biochar, which prevented the agglomeration of TiO₂ and enhanced the instability. The highest ammonia-nitrogen removal efficiency (100% at 60 ℃ and over 70% at 30 ℃)was observed at the conditions of 20% TiO₂ loading, 150 mL/min aeration rate, pH 11.0, and under 254 nm UV light irradiation. The final product contained little nitrite and exclusive nitrate, indicating the excellent catalytic selectivity of TiO₂/biochar composite, which can oxide ammonia-nitrogen to N₂. In conclusion, TiO₂/biochar composite is anenvironmentally-friendly and highly efficient photocatalyst complex for the removal of ammonia-nitrogen at low concentrations.