In order to improve the photocatalytic property of a tungsten trioxide (WO 3 )/titanium dioxide (TiO 2 ) composite, a novel structure -that is, a hollow microsphere with a mesoporous wall -was fabricated. The relations between the interior characteristics and the optical, photoelectric and photocatalytic properties of the samples were investigated. The results show that the tungsten (W)/titanium (Ti) ratio and the crystallinity and diameter of the crystallite of the sample determine its optical property. The photoelectric conversion property of the sample is related to its electron ability transfer and optical property. The photocatalytic property of the sample is relevant to its optical property and interior structures, in particular the particle microstructure of the sample, the dispersion of titanium dioxide and tungsten trioxide crystallites and their contact relationship at the mesoscale. In terms of application, it is the hollow microsphere with a mesoporous wall that takes a key role. These set a connection between the property and mesostructure of the sample, which facilitates the adjustment of the property of tungsten trioxide/titanium dioxide composite. Notation