A　pilot-scale　modified　UCT　step　feed　process　was　proposed　to　treat　the　municipal　wastewater　with　lower　COD/N　in　a　large-scale　wastewater　treatment　plant.　Effects　of　influent　distribution　ratios　and　nutrients　ratios　(COD/N,　COD/P　and　TN/P)　on　nutrients　removal　capabilities　were　importantly　investigated.　The　removal　mechanisms　of　organics　and　nutrients　and　sludge　characteristics　were　ultimately　discussed.　According　to　the　continuous　experiments,　the　stable　and　high　process　performance　was　obtained.　The　average　COD　removal　efficiencies　and　effluent　concentration　of　(83.8　±　3.86)%　and　(43.7　±　8.35)　mg/L　were　achieved　in　the　influent　COD　loading　of　0.79-0.93　kg/(m　3　·　d).　The　COD　removal　in　anaerobic　and　anoxic　zones　accounted　for　60.2%-76.2%.　With　the　influent　distribution　ratio　of　40%:　30%:　30%,　as　much　as　88.2%　of　TN　removal　efficiency　was　observed.　It　should　be　considered　the　removal　of　32.8%　through　simultaneous　nitrification　and　denitrification　process.　The　average　effluent　NH　4　+-N　and　TN　were　(0.21　±　0.20)　mg/L　and　(7.90　±　1.27)　mg/L,　respectively.　It　was　extremely　important　that　as　much　as　32.6%-39.5%　of　the　denitrifying　phosphorus　accumulation　organisms　contributed　to　the　high　phosphorus　removal　efficiency　of　97.2%.　A　linear　positive　relationship　was　observed　between　nitrogen　removal　efficiency　and　COD/N　in　the　range　of　4.64　and　7.41　(R　2=0.96).　Phosphorus　removal　efficiency　was　found　to　be　a　function　of　the　influent　COD/P　and　TN/P,　varying　from　35.0　to　92.5　and　from　6.24　to　12.5,　respectively　(R　2=0.87　and　R　2=0.89).　In　addition,　the　great　sludge　settleability　was　obtained　with　the　mean　SVI　of　(82.6　±　4.99)　mL/g.