This study provides a new thinking for the efficient utilization of permanganate (Mn (VII)) in eutrophic water treatment. Eutrophic water contained a large amount of extracellular polymeric substances (EPS) with reduction and chelation; this study used phenol as typical organic matter and cyanobacteria EPS as a representative EPS to explore the mechanism by which EPS influences the oxidation of phenol by Mn(VII) at pH 5.0-9.0. The results showed that under the condition of pH 5.0-7.0, adding 0.2-10 mg/L EPS to the Mn(VII) system could effectively improve the oxidation efficiency of Mn(VII) for phenol. EPS promoted the continuous formation and stability of in situ EPS-MnO2 colloids and significantly enhanced the oxidation of Mn(VII). EPS also combined with phenol and increased the electron cloud density to promote the oxidation of phenol by Mn(VII).