The treatment scale of a township wastewater treatment plant (WWTP) in Jiangsu is improved from 5 000 m3/d to 20 000 m3/d, and the effluent quality is improved from the first level A standard of Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants (GB 18918—2002) to Discharge Limits for Main Water Pollutants from Municipal Wastewater Treatment Plant and Key Industries in Taihu Area (DB 32/1072—2018) and other areas of Taihu area mainly for TN and NH3-N. Due to the land restriction, improvement of nitrogen removal standards, and scale expansion, the multimode AAO process is adopted for the new construction and reconstruction of the biochemical section, and the current three-ditch oxidation ditch is reconstructed to AAO so as to achieve the expansion target. In the advanced treatment section, the mixing, corrugated plate flocculation, lateral flow inclined-plate sedimentation tank and fiber turntable filter are adopted to achieve TP and SS up to standards. This process has the advantages of high land utilization, stable operation, low treatment cost and simple operation management, and is suitable for township WWTPs.