A novel hydrogel photocatalyst (p(HEA-APTM)-BiOI) was synthesized by irradiation polymerization and chemical precipitation method, while employed as peroxymonosulfate (PMS) activator to enhance methylparaben (MP) degradation. The structure, morphology and physicochemical properties of the prepared p(HEA-APTM)-BiOI were characterized by XRD, XPS, SEM, TEM, FTIR and BET. The experimental results revealed that the MP catalytic degradation by p(HEA-APTM)-BiOI activated PMS can achieve the best performance under the visible light irradiation. In addition, the parameters including the molar radio of [PMS]/[MP], initial pH, Cl- and HCO3- were also investigated in detail. It was worth noting that p(HEA-APTM)-BiOI also effectively eliminated MP in the absence of visible light. Based on the quenching experiment, O-1(2), h(+) and center dot O-2(-) were determined as the dominant active species contributing to the catalytic oxidation process in the p(HEA-APTM)-BiOI/PMS/Vis system, and the possible degradation mechanism was also elaborated. Eventually, the possible pathways of MP degradation were deduced from several intermediates identified by HPLC-MS.