Abstract: In order to improve the adsorption performance of sugar beet pulp as a biosorbent, sugar beet pulp(SBP) was modified with quaternary ammonium salt tetrabutylammonium bromide(TBAB) to obtain the modified adsorbent TBAB-SBP. The adsorption performance of TBAB-SBP on nuclear fast red was explored. Its kinetics and thermodynamics were analyzed, and the chemical structure and surface morphology of TBAB-SBP were characterized by using FT-IR, XRD and SEM. The results showed that TBAB could be effectively loaded on the surface of SBP, and the types and number of functional groups increased. The static adsorption process conditions for nuclear fast red on TBAB-SBP in wastewater were pH value of the solution 2.0, 100 mL of nuclear fast red solution with mass concentration of 100 mg/L, amount of adsorbent 0.6 g, treatment time 180 min, adsorption temperature 25 ℃. Under these conditions, the pigment removal rate of TBAB-SBP was 94.44%, which was about 12% higher than that of SBP; the adsorption equilibrium data conformed to the Langmuir isotherm model; the adsorption process was a spontaneous exothermic process; the TBAB-SBP adsorption nuclear fast red process conformed to the qseudo-second-order equation.