A novel BiOI/Bi12O17Cl2 heterojunction composite was fabricated via a facile deposition–precipitation method. The surface loading of a portion of BiOI strongly broadened the visible light absorption of Bi12O17Cl2 from 500–600nm. The photoelectric performance measurements show that the tightly contacted BiOI/Bi12O17Cl2 heterojunction largely strengthened the spatial separation efficiency of photocharges under visible light. Furthermore, BiOI/Bi12O17Cl2 applying to degrade two contaminant models, methyl orange (MO) and phenol, displayed much higher photocatalytic activity than the single Bi12O17Cl2 and BiOI under visible light (λ>400nm). This is a successful Bi-based semiconductor composite photocatalytic system that can efficiently remove the organic contaminants in wastewater.