Elemental mercury removal in coal-fired power plants is the key to global mercury pollution control, and photocatalytic oxidation is an effective and stable method. As a typical bismuth-based photocatalyst, BiOIO3 has a large band gap which is not conducive to the absorption and utilization of visible light, and its specific surface area also limits the diffusion and adsorption of reactants. In this work, pink BiOIO3 (PB) was first prepared successfully via vacuum calcination under absolute pressure of 1*10-3 Pa. The specific surface area of pink BiOIO3 is significantly increased to 44.52m2/g, which is 1.5-times compared with the traditional BiOIO3 prepared by hydrothermal method (only 29.60 m2/g). Abundant oxygen vacancy defects exist on sample surface, and the formed local BiOI Zero-dimensional (0-D) nanodots provide heterojunction-like effect combined with the BiOIO3, obtaining better photocatalytic property in the oxidation of elemental mercury. The as-prepared pink BiOIO3 and the preparation technology also have strong application potential in the field of energy and environment.