Abstract: Methyl 2, 4-dihydroxybenzoate (MDB) is a relatively stable hydroxylated product of methylparaben (MeP) during advanced oxidation process (AOPs), which has more toxicity than pure MeP. And its presence in the environment will caused potential risks to ecosystems. Photocatalytic degradation of MDB was performed for the first time under visible light irradiation using I-doped Bi4O5Br2 photocatalyst. Compared with pure Bi4O5Br2, I-doped Bi4O5Br2 photocatalyst exhibited enhanced photocatalytic activity (0.038 min-1) in the degradation of MDB under visible light, showing approximately 5 times than that of pure Bi4O5Br2. The better separation efficiencies of the photogenerated electron-hole pairs and visible light absorption are considered to be the key reasons for the enhanced photocatalytic activity of I-doped Bi4O5Br2. Photogenerated holes and superoxide radicals were identified as the main reactive species by scavenger experiments.