Tetracycline cannot be effectively degraded in wastewater treatment. Therefore, the development of excellent photocatalysts is of significant importance for environmental protection. In this study, a β-Bi2O3/BiOCl heterojunction photocatalyst with hollow flower-like microspheres was successfully synthesized by the in-situ reaction of HCl and β-Bi2O3 hollow spheres. The prepared samples are characterized by Scanning electron microscopy, Transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N2 physical adsorption, UV-vis diffuse reflectance spectroscopy, and Photoluminescence. Then, research on the photocatalytic performance for the degradation of tetracycline hydrochloride was conducted. The results show that the photocatalytic performance of the β-Bi2O3/BiOCl composite is significantly better than the β-Bi2O3 and BiOCl. The increase in photocatalytic activity is due to the formation of a heterojunction between β-Bi2O3 and BiOCl, which effectively promotes the separation of photogenerated electron-hole pairs. Additionally, the heterojunction nanocomposite demonstrated the outstanding photocatalytic stability after five cycles, which indicates that the material can be used for water environment purification. This paper provides assistance for studying the photocatalytic mechanism of heterojunction photocatalytic materials.