The invention relates to a composite double-Z-shaped photocatalyst BiFeO3/CuBi2O4/BaTiO3, and a preparation method and application thereof, the BiFeO3/CuBi2O4/BaTiO3 preparation method includes the following steps of dissolving BiFeO3 powder, CuBi2O4 powder and BaTiO3 powder in deionized water according to the molar ratio of 1:2:1, fully stirring the deionized water, boiling the deionized water for 30 minutes, and performing complete drying and grinding at the temperature of 80 DEG C; performing calcination in a muffle furnace at the temperature of 280 DEG C for 3 hours, and performing grinding to obtain the BiFeO3/CuBi2O4/BaTiO3 composite catalyst, the composite catalyst can be used for efficient photocatalytic degradation of antibiotics under the action of sunlight.