The　simultaneous　anammox　and　denitrification　granular　process　effectively　removes　nitrogen　and　organic　matter,　but　its　optimization　for　variable　nitrogen　loading　rates　(NLRs)　is　challenging　due　to　regulatory　complexities　and　delays.　This　study　developed　and　evaluated　a　modified　model　to　determine　an　effective　operational　strategy,　using　data　from　batch　tests　and　long-term　experiments.　Simulations　revealed　a　spatial　cross-distribution　of　anammox　bacteria　and　heterotrophic　denitrification　bacteria　(HDB)　within　the　granules,　and　HDB　tended　to　grow　on　the　surface.　Higher　NLRs　(from　0.35　to　14.06　kg　N　(m(3)d)(-1))　extended　the　time　to　reach　steady　state,　limiting　the　treatment　capacity　to　7.73　kg　N　(m(3)d)(-1)　at　NH4+-N/NO2--N/COD　=　1:1.32:　0.5.　At　different　influent　NH4+-N　concentrations　(NH4+-N-Inf:　40,　150,　and　300　g　N　m(-3)),　single-factor　simulations　showed　that　optimal　nitrogen　removal　and　granular　stability　were　achieved　at　specific　NO2--N/NH4+-N　ratios　(1.2-1.3),　C/N　ratios　(1.2-0.8),　and　particle　sizes　(500-1000　mu　m).　Adjusting　the　NO2--N/NH4+-N　(1.0-1.6)　and　C/N　ratios　(0.2-1.2)　zones　synergistically　improved　the　operational　efficiency　(TN　removal　efficiency　＞90　%).　Notably,　elevated　NH4+-N-Inf　amplified　single-factor　effects,　complicating　efficient　optimization.　These　insights　significantly　inform　the　process　design　and　operation　in　varying　NLR　wastewater　contexts.