Novel Z-Scheme CuBi2O4/β-Bi2O3 composite photocatalysts with different mass ratios and calcination temperatures were firstly synthesized by the hydrothermal method following a temperature-programmed process. The morphology, crystal structure, and light absorption properties of the as-prepared samples were systematically characterized, and the composites exhibited enhanced photocatalytic activity toward diclofenac sodium (DS) degradation compared with CuBi2O4 and β-Bi2O3 under visible light irradiation. The optimal photocatalytic efficiency of the composite, achieved at the mass ratio of CuBi2O4 and β-Bi2O3 of 1:2.25 and the calcination temperature of 600 °C is 92.17%. After the seventh recycling of the composite, the degradation of DS can still reach 82.95%. The enhanced photocatalytic activity of CuBi2O4/β-Bi2O3 is closely related to OH•, h+ and O2•−, and the photocatalytic mechanism of CuBi2O4/β-Bi2O3 can be explained by the Z-Scheme theory.