Using waste cigarettes as raw materials, carbonizing them and then introducing amino functional groups to prepare ammoniated tobacco biocarbon adsorbent (ATC), to study the effects of pH, dosage, temperature, and adsorption time on the adsorption of U(VI) by ATC . The mechanism is analyzed by scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and other techniques. The results show that: when the initial concentration is 250mg/L, pH=6, dosage is 0.2 g/L, temperature is 40 ℃, adsorption time is 210 min, the maximum adsorption capacity of ATC for U(VI) is 495.04mg/g . The adsorption kinetics conforms to the quasi-second-order kinetic model; the Langmuir adsorption isotherm model can better describe the adsorption behavior of ATC on U(Ⅵ). U(Ⅵ) adsorption removal mechanism mainly includes electrostatic interaction, coordination and complexation with amino (-NH2), hydroxyl (-OH), carboxyl (-COOH), and the "π-π" interaction of Si-O-Si effect. Through 5 adsorption-desorption tests, it is found that the U(Ⅵ) removal rate is above 86.71%. This study shows that ammoniated tobacco leaf biochar has the potential to treat and repair the pollution of weakly acidic wastewater containing U(Ⅵ).