To further remove the organic pollutants residual in the biologically pretreated coal chemical industry wastewater, three-dimensional electro-Fenton system was established by involving Fe loaded sludge deserved activated carbon (SAC-Fe) from sewage and waste iron sludge, and was introduced in the advanced treatment of biologically pretreated coal chemical industry wastewater. Process parameters were optimized by response surface methodology (RSM) coupled with central composite design, and the catalytic reaction mechanism involved in system was discussed. Results show that SAC-Fe exhibited high adsorption performance to the pollutants in the wastewater. The maximum adsorption content calculated with Langmuir model was 101.1 mg/g. The optimal process parameters were determined as 16.78 mA/cm² of current density, 14.75 mmol/L of equivalent Fe content and pH 3.92, with the observed TOC removal efficiency of 67.12%. The catalytic reaction mechanism was discussed based on the analysis of H₂O₂ and ·OH contents and adsorption effect. SAC-Fe exhibited high electro-catalytic activity in three-dimensional electro-Fenton system. SAC-Fe as catalytic particle electrode significantly promoted the production amount and rate of H₂O₂ and ·OH. Adsorption effect improved ·OH and organics removals. Thus three-dimensional electro-Fenton with SAC-Fe as catalytic particle electrode exerted excellent performance in the advanced treatment of coal chemical industry wastewater.