The　significance　of　inorganic　carbon　(IC)　for　anaerobic　ammonium　oxidation　(anammox)　bacteria　has　been　verified.　However,　the　regulation　of　metabolic　pathways　under　IC　stress　is　not　clear,　limiting　the　optimization　of　IC　supply.　In　this　study,　the　regulatory　pathways　at　IC　concentration　of　5-150　mg/L　were　explored　to　achieve　optimal　control　of　IC.　The　results　show　that　the　changes　of　metabolic　pathway　under　IC　stress　determined　anammox　characteristics.　At　IC　concentration　of　5　mg/L,　the　anammox　activity　distinctly　decreased　due　to　the　guanosine　tetraphosphate　(ppGpp)　-mediated　regulation　under　IC　limitation.　With　less　than　15　mg/L　of　IC,　the　decrease　of　carbon　fixation　limited　the　biosynthesis　of　gluconeogenesis　and　amino　acids,　causing　the　decline　of　extracellular　polymeric　substance　synthesis.　With　more　than　50　mg/L　of　IC,　the　improvement　of　purine　and　pyrimidine　metabolism　enhanced　the　electron　transport　capacity　and　growth　potential　of　anammox　bacteria.　This　study　provides　metabolic　insights　into　IC　influence　on　anammox　consortia　and　a　novel　method　of　IC　concentration　optimization　using　metabolomics　analysis.