Relating to environmental protection technologies, the invention provides a new treatment method for domestic sewage. The following problems exist in the existing domestic sewage treatment process: the competition of anaerobic phosphorus release and nitrogen removal by denitrification for carbon source; the metabolic cycle contradiction of nitrobacteria, heterotrophic bacteria and phosphorus-accumulating bacteria; the competition of nitrobacteria and heterotrophic bacteria for oxygen; and high energy consumption, high cost and troublesome operation. The method includes the steps of: letting domestic sewage enter an anaerobic tank, making the sludge-water mixed liquid of the anaerobic tank enter a sedimentation tank, enabling the supernatant of the sedimentation tank to flow automatically to an aerobic biofilm nitrification tank, simultaneously conducting aeration to supply oxygen, overflowing sludge into an anoxic tank, making the sludge-water mixed liquid of the anoxic tank enter a sedimentation tank, discharging the supernatant of the sedimentation tank, and letting the sludge flow back to the anoxic tank, with the effluent water meeting the first class A discharge standard of the national "pollutant emission standard for municipal wastewater treatment plants" (GB18918-2002). The method provided by the invention has the advantages of good sewage treatment effect, no need foradditional carbon source, low energy consumption, low process construction cost, convenient operation, environmental protection, and is conducive to improving the water environment quality.