A gas diffusion electrode (air electrode) with a high current efficiency of electro|synthesizing H 2 O 2 using O 2 in air was prepared. The several systems with air electrode as cathode of ele ctro|synthesizing H 2 O 2 on the reaction spot for degrading aniline in aqueous--electro|Fenton system, photo|excitation electro|H 2 O 2 system and photo|electro|Fenton system, were developed. Th e rates of decomposition of H 2 O 2 and mineralization of anil ine were experimentally measured respectively under different conditions, and th e results indicated there has an excellent parallel relation between decompositi on rate of H 2 O 2 and mineralization rate of aniline. Especia lly, photo|electro|Fenton system, where H 2 O 2 is decompose d the fastest, is the best system of oxidizing and degrading organic toxicants. Compared photo|electro|Fenton system with photo|Fenton system, important role is revealed in the interface of air electrode. In this paper, the mineralizatio n mechanism of aniline in the photo|electro|Fenton system was also discussed. A gas diffusion electrode (air electrode) with a high current efficiency of electro | synthesizing H 2 O 2 using O 2 in air was prepared. The several systems with air electrode as cathode of ele ctro | synthesizing H 2 O 2 on the reaction spot for degrading aniline in aqueous - electro | Fenton system, photo | excitation electro | H2O2 system and photo | electro | Fenton system, were developed. Th e rates of decomposition of H 2 O 2 and mineralization of anil ine were experimentally measured respectively under different conditions, and th e results has there an excellent parallel relation between decompositi on rate of H 2 O 2 and mineralization rate of aniline. Especia lly, photo | electro | Fenton system, where H 2 O 2 is decompose d the fastest, is the best system of oxidizing and degrading organic toxicants. Dependent photo | electro | Fenton system with photo | Fenton system , important role is revealed in the interface of air electrode. In this paper, the mineralizatio n mechanism of aniline in the photo | electro | Fenton system was also discussed.