In this paper, electrolysis and hypochlorite oxidation methods are adopted for the preparation of potassium ferrate, focusing on increasing the production yield and product’s purity. The oxidation of benzopyrene by potassium ferrate was investigated. The yield of potassium ferrate prepared with hypochlorite at optimized conditions is 21% higher than that of using electrolysis method. With the presence of hypochlorite, various conditions of oxidation reaction were determined as following: reaction temperature 25°C, re-crystallization temperature of -5 °Cand reaction time 40 minutes, which all contribute a yield of 80%. Spectrophotometric was used to analyze the purity of the product, which was measured up to 97%. XRD and IR were used to characterize the final product. The aqueous stability of potassium ferrate at various pH values was investigated. It was found that potassium ferrate solution had a maximum stability at pH 9-10.5. With three-dimensional excitation emission matrix fluorescence spectrosopy technique, the reaction of ferrate and benzopyrene (BaP) in aqueous phase which is a representative polycyclic aromatic hydrocarbon, was also investigated. The maximum degradation (49.5%) of BaP was gained at conditions of pH 9.5, Fe(VI): BaP molar ratio of 1:5, reaction time of 3 hours.