In　this　work,　a　novel　model　was　established　to　optimize　the　C/N　in　the　aerobic　section　based　on　the　regulation　of　the　influent　distribution　ratio　of　each　aerobic　section,　using　pre-decarbonized　wastewater　and　municipal　wastewater　as　target　wastewater.　This　work　was　aiming　at　achieving　the　stable　operation　of　the　partial　nitrification-anammox　(PN/A)　process　under　realistic　conditions.　Four　groups　of　sequential　batch　reactors　(SBR)　with　the　same　specifications　run　in　oxic/anoxic/oxic/anoxic　(O/A/O/A)　mode,　R1,　R2,　R3,　and　R4　operated　in　the　step-feed　mode　with　the　influent　distribution　ratios　(pre-decarbonized　wastewater:　municipal　wastewater)　of　1:0,　2:1,　1:1,　and　1:2.　The　results　illustrated　that　R1failed　to　realize　the　PN/A　process　and　total　nitrogen　removal　efficiency　(NRE)　was　only　60.2%.　Along　with　the　decreasing　influent　distribution　ratio,　R2,　R3,　and　R4　completed　the　PN/A　process　on　the　34th,　30th,　and　36th　days,　which　NRE　reaching　71.8%,　80.3%,　and　74.1%.　Among　them,　R3　had　the　optimized　performance　with　best　stability,　and　the　contribution　of　anammox　reaching　83.9%.　It　was　revealed　that　sludge　exhibited　excellent　settling　characteristics　and　optimal　particle　size.　Moreover,　high-throughput　data　also　demonstrated　the　abundance　of　ammonia-oxidizing　bacteria　(Nitrosomonas)　and　anammox　bacteria　(Candidatus_Kuenenia)　at　2.74%　and　12.17%.　These　microbial　populations　synergized　effectively　with　aerobic　heterotrophic　bacteria　(AHB).　Hence,　the　step-feed　model　could　be　conductive　to　achieve　a　stable　PN/A　process.　The　influent　distribution　ratio　of　1:1was　suggested　as　a　suitable　reference　value,　fostering　better　enrichment　and　balance　of　functional　microorganisms.　©　2024　Chinese　Society　for　Environmental　Sciences.　All　rights　reserved.