An ecofriendly and cheap photocatalyst is crucial for realizing practical photocatalysis applications. Many inorganic materials have modular structures in which individual units are responsible for different functions. [Bi2O2]2+ slabs with an alpha-PbO-type structure and simple halide layers are effective spacers in some layered functional materials. Previous reports have mainly discussed electronic reasons for the different photocatalytic activities of layered PbBiO2X-type materials (X = Cl, Br, I). To the best of our knowledge, nanocomposite semiconductors consisting of PbBiO2I/g-C3N4 have not been reported in the literature. In this study, PbBiO2X/gC3N4 composites were isolated and characterized by FE-SEM-EDS, XRD, HR-XPS, TEM, PL, BET, FT-IR, and UV-vis-DRS. By degrading crystal violet (CV) and 2-hydroxybenzoic acid (HBA) in an aqueous solution under visible-light irradiation, the photocatalytic activities of PbBiO2I/g-C3N4 are discussed further. In particular, the catalytic performance illustrates the best reaction rate constants of 0.3259 h- 1 using the PbBiO2I/g-C3N4 composite as the photocatalysts; these are 13.7 and 9.1 times higher than those of PbBiO2I and g-C3N4, respectively. The quenching effects of different scavenger results demonstrate that reactive O2 center dot plays the major role and center dot OH, h+, and 1O2 play the minor role in CV degradation.