A novel BiOBr/BiFeO₃ heterojunction sonocatalyst was prepared and characterized. The sonocatalytic activity of BiOBr/BiFeO₃ composite was evaluated by the catalytic degradation of ciprofloxacin. BiOBr/BiFeO₃ composite combined with persulfate had excellent sonocatalytic activity for ciprofloxacin degradation under ultrasonic irradiation, and the degradation rate was 73.64% ± 7.96%. The formation of Z-type heterojunction of BiOBr/BiFeO₃ and the generation of hydroxyl radical, superoxide anion and hole were the key to the catalytic activity of BiOBr/BiFeO₃. Free radicals will attack the positions of piperazine ring, cyclopropyl, C-F bond, carboxyl group and ethylenic linkage in ciprofloxacin structure, and gradually degrade ciprofloxacin through multiple paths. After the sonocatalytic degradation, the bacteriostatic effect of the solution decreased significantly and the environmental pollution decreased significantly. As a sonocatalyst, BiOBr/BiFeO₃ composite has good degradation and removal effect on ciprofloxacin and has practical application potential. Meanwhile, it lays a foundation for the further practical application of sonocatalytic degradation technology.