The wastewater treatment plant based on biological aerated filter faces the upgrading reconstruction to achieve the GB code first-level of wastewater discharge. Studies on the advanced treatment process involving chemical phosphorus removal, air-floated oil removal, hydrolysis acidification and the anoxic/oxic biological aerated filter were conducted, the feasibility of the process and the optimal parameters were determined. the feasibility of the process and the optimal parameters were determined. For pre-denitrification, the reflux ratio was 125 %, the hydraulic retention time was 20 min. The cost of construction and operation were calculated. The theoretical evidence and database can be used to the reference for the upgrading reconstruction of the similar wastewater treatment plant.