The control of pollutants has attracted considerable recent attention. The removal technology of antibiotics as pollutants becomes a challenge, especially water treatment technology based on photocatalytic degradation of antibiotics. In this paper, WO3 was prepared by a hydrothermal method, and the S-scheme heterojunction BiOBr/WO3 was constructed by a precipitation method at room temperature. Compared with BiOBr and WO3, the formation of S-scheme heterojunction improves the photocatalytic activity, and reduces the recombination rate of photogenerated electron-hole pairs. The optimum photocatalytic performance of BiOBr/WO3 with a mass fraction of 20% can be achieved, and the degradation rate for ciprofloxacin (CIP) is 94.93% within 120 min. Based on the electron spin resonance and radical trapping experiments, ·O2- is a primary active component in the photocatalytic degradation of CIP. The results of high-performance liquid chromatography-mass spectrometer system indicate that six intermediates are produced during the degradation of CIP, which are eventually mineralized into CO2, H2O and other inorganic ions.