WO3, a typical transition metal oxide, has attracted great attentions in photocatalysis due to its abundant reserves, environmentally friendly, good physicochemical stability, visible-light response and proper band edge positions, etc.. Nevertheless, several drawbacks such as the low utilization of solar energy, high charge carrier recombination rate, weak reduction ability and limited reactive sites lead to a poor photoactivity, thus restricting the industrial application. Various modification strategies are explored and utilized to promote the photocatalytic activity. It is thus necessary to review recent development on WO3-based photocatalysts that might provide a general guidance for designing high-efficient WO3 catalyst systems. Morphology control can tailor WO3 nanomaterials to expose a highly active crystal plane, which is beneficial for reactivity. Low-dimensional nanomaterials possess the larger surface area and large quantity of unsaturated coordination sites, then accelerates the surface reaction. The charge carrier migration efficiency can be increased in a small size of catalysts due to the limited transportation distance. However, the preparation of low-dimensional WO3 with a precise structure and a stable crystal plane is an obstacle. Oxygen vacancy in WO3 materials can capture the photoinduced electrons and hence suppress the recombination of electron-hole pairs. Moreover, the creation of oxygen affects the band structure that can broaden the light absorption and enhance the redox ability. Nevertheless, excessive oxygen vacancy may induce the structural instability. Thus, the precise control of oxygen vacancy in WO3 is the key point. Metal or non-metal doping can induce the lattice distortion and then affect the physicochemical properties of semiconductor. Doping element acts as an electron acceptor that contributes to the ultrafast charge separation. Also, the introduction of impurity energy level favors the reduction of energy band. The more comprehensive understanding of the reactive sites in doping catalysts still needs further exploitation. Loading co-catalyst in WO3 benefits for charge carrier separation and migration. Metal co-catalyst can increase the solar energy utilization resulting from its localized surface plasmon resonance effect. The current common co-catalysts focus on noble metal that is high cost. The pursuit of abundant reserves materials is highly desired for commercial application. The construction of II-type, Z-type and S-type WO3-based heterojunctions is an effective strategy for solving the problems of single materials. The charge carriers in II-type heterojunction tend to transfer from agreatability of positions to the low positions, which are beneficial for spatial separation of electron-hole pairs, but the redox ability weakens. The unique merit in Z-scheme and S-scheme heterojunction is an intense redox ability maintained in separate components, thus triggering the unique photoreaction. Summary and prospects WO3, as a typical oxidation photocatalysts, had some advantages such as visible light harnessing, suitable band edge position, good physicochemical stability, cost benefit and environmental friendliness. It was widely utilized in various photocatalytic areas like pollutant removal, water splitting, CO2 photoreduction and nitrogen fixation. This review summarized the developed modification strategy for improving the photocatalytic performance of WO3 nanomaterials in recent years, i.e., morphology regulation, oxygen vacancy regulation, element doping, cocatalyst loading, and construction of heterojunctions. Through these modification approaches, the band structure could be modulated and then increase the solar energy utilization. The spatial separation of electron-hole pairs could be thus accelerated. And electrons and holes with an intense redox ability could participate into the catalytic reactions. Besides, the surface structure and interfacial structure could be regulated, exposing themore unsaturated coordination sites and thereby accelerating the surface reaction. Despite the tremendous progress, further improvements are still urgently required to satisfy the industrial application. The cost-effective and large-scale preparation of WO3 nanomaterials with uniform size and unique structure is always a challenge. The understanding of the actual reactive sites in WO3 is important for getting insights into the structure-reactivity correlations. The synchrotron radiation and in-situ spectroscopy, the structural configurations for catalysts and the formation of intermediates during photoreaction could be monitored by some advanced characterizations like environmental transmission electron microscope, and aberration scanning transmission electron microscope. Combining the simulation with the related experiments could favor the in-depth understanding the mechanism during photocatalysis including reactant adsorption, diffusion and surface reaction, along with the charge carrier kinetics composed of light excitation, carrier migration and reaction barrier. These key points are crucial for designing high-efficient photocatalytic systems.