Multi-heterojunction is more promising than single-heterojunction in photocatalysis due to the availability of more interfaces between each component. However, its photocatalytic activity is highly dependent on the contact mode of individual component. In this work, we assemble TiO2-WO3-Pt multi-heterojunction microspheres by ultrasonic spray pyrolysis and focus on their contact mode governed photocatalytic activity. The results reveal that highly crystalline WO3 nanosheets as building blocks could particularly enhance the photocatalytic activity of TiO2/WO3 system toward degrading gaseous acetaldehyde and isopropyl alcohol. Furthermore, loading of Pt nanoparticles on WO3 nanosheets could facilitate to a more prominent enhancement of activity than that of TiO2/Pt, benefiting from the two-electron reduction of oxygen at the interface of WO3/Pt. Meanwhile, high crystallinity of WO3 nanosheets allows a loading amount of Pt as low as 0.04 wt% in TiO2-WO3-Pt system, which reduces the catalyst cost in comparison with the conventional amount of 1wt%.