Iodate oxygen bismuth (BiOIO3) is a kind of bismuth-based materials with favourable photocatalytic performance which has profound effect on the problem of severe energy shortage and environmental pollution. In this work, a high-efficiency photocatalyst of bismuth vanadate combined with iodate oxygen bismuth (BiVO4/BiOIO3) are prepared via a single hydrothermal method. The as-prepared novel photocatalyst exhibit high photocatalytic performance resulting from high visible light absorbance ability and the formed heterojunction, which is beneficial to the generation and migration of photonic electron hole pairs and inhibit their recombination meanwhile. The photocatalytic oxidation ability of samples is evaluated by removal efficiency of element mercury (Hg-0), which is very-hard to be oxidized, under LED (9W) light radiation with the wavelength of approximately 380-450nm. The experimental results have indicated that the as-prepared composite catalyst show higher efficient in oxidizing Hg-0, which could reach up to about 75%. Furthermore, the photocatalytic reaction mechanism about double electron transfer phenomenon between heterostructures is proposed based on characterization and experimental results. [GRAPHICS] .