This review summarizes recent advances in WO₃-based composite photocatalysts, focusing on their synthesis, catalytic mechanisms, and diverse applications. WO₃ is a promising semiconductor photocatalyst due to its good visible light response and excellent valence band hole oxidation properties. However, its conduction band edge is more positive than that of H⁺/H₂, limiting electron utilization. To overcome these limitations, various modification strategies have been applied, including doping, photosensitization, noble metal deposition, and semiconductor recombination. Composite materials have received significant attention, with nearly half of the modification efforts in the past five years focused on composite construction. The review systematically summarizes the synthesis methods, structure-activity relationships, and applications of WO₃-based composite photocatalysts in CO₂ reduction, hydrogen production, nitrogen fixation, and pollutant removal. It also discusses the structure and physicochemical properties of WO₃, including its crystal phases, band structure, and atomic arrangement. The review highlights the potential of WO₃-based composite photocatalysts in environmental purification and clean energy production, and proposes future development directions. The review aims to provide a reference for researchers in the field of photocatalysis. Keywords: WO₃-based composite photocatalysts; Intrinsic characteristic; Preparation method; Reaction mechanism; Applications.This review summarizes recent advances in WO₃-based composite photocatalysts, focusing on their synthesis, catalytic mechanisms, and diverse applications. WO₃ is a promising semiconductor photocatalyst due to its good visible light response and excellent valence band hole oxidation properties. However, its conduction band edge is more positive than that of H⁺/H₂, limiting electron utilization. To overcome these limitations, various modification strategies have been applied, including doping, photosensitization, noble metal deposition, and semiconductor recombination. Composite materials have received significant attention, with nearly half of the modification efforts in the past five years focused on composite construction. The review systematically summarizes the synthesis methods, structure-activity relationships, and applications of WO₃-based composite photocatalysts in CO₂ reduction, hydrogen production, nitrogen fixation, and pollutant removal. It also discusses the structure and physicochemical properties of WO₃, including its crystal phases, band structure, and atomic arrangement. The review highlights the potential of WO₃-based composite photocatalysts in environmental purification and clean energy production, and proposes future development directions. The review aims to provide a reference for researchers in the field of photocatalysis. Keywords: WO₃-based composite photocatalysts; Intrinsic characteristic; Preparation method; Reaction mechanism; Applications.