Abstract: In order to meet the requirements of advanced treatment of effluent from biochemicaltreatment of printing and dyeing wastewater,activated carbon ( AC) particles loaded with manganese di-oxide were prepared by impregnation and thermal reduction method. The morphology and structure ofthe modified activated carbon ( AC-Mn and AC-O-Mn) were characterized by scanning electron mi-croscopy ( SEM) ,X-ray diffraction ( XRD) and Raman spectroscopy. In a three-dimensional electrodesystem,the effect of modified activated carbon particle electrode on the degradation of COD in the efflu-ent from biochemical treatment of printing and dyeing wastewater was investigated. The results showedthat manganese-loaded activated carbon particle electrode with a loading amount of 4.4% could be pre-pared using manganese sulfate as the precursor. The main form of manganese in activated carbon wasmanganese dioxide. Oxidation destroyed the structure of activated carbon and was not conducive to theloading of manganese dioxide. The effluent from biochemical treatment of printing and dyeingwastewater was treated by the three-dimensional electrode system. After 15 minutes of electrolysis,theconcentration of COD was reduced to 47 mg /L,and the removal rate of COD could reach 83.7% whichwas 41% higher than that with unmodified activated carbon particle electrode. Close-