Abstract Novel hierarchical sheet-on-sheet WO3/g-C3N4 (WOCN) composites were successfully fabricated by simple calcination method using acid-treated SrWO4/g-C3N4 as precursors. The morphological observation showed that WO3 nanosheets were closely anchored on the surface of g-C3N4 nanosheets to construct a hierarchical nanostructure. The as-synthesized WOCN composites exhibited a significantly higher photocatalytic activity towards the photocatalytic degradation of rhodamine B (RhB) compared to pristine g-C3N4 and WO3 under simulated sunlight irradiation. The optimum photocatalytic activity of the WOCN at a WO3 mass content of 34.6% was 6.5 and 3.0 times higher than that of pristine WO3 and g-C3N4, respectively. The enhanced photocatalytic activities of WOCN composites were attributed to the formation of hierarchical heterostructure, which provided larger specific surface area, better visible-light absorption capability, reduced the recombination of photogenerated electron-hole pairs and enhanced separation efficiency of charge carriers. A Z-scheme photocatalytic mechanism was proposed according to active species trapping experiments.