Microalgae　photobioreactor　(PBR)　is　a　kind　of　efficient　wastewater　treatment　system　for　nitrogen　removal.　However,　there　is　still　an　urgent　need　for　process　optimization　of　PBR.　Especially,　the　synergistic　effect　and　optimization　of　light　and　flow　state　poses　a　challenge.　In　this　study,　the　computational　fluid　dynamics　is　employed　for　simulating　the　optimization　of　the　number　and　length　of　the　internal　baffles,　as　well　as　the　aeration　rate　of　PBR,　which　in　turn　leads　to　the　optimal　growth　of　microalgae　and　efficient　nitrogen　removal.　After　optimization,　the　Light/Dark　cycle　of　the　reactor　B　is　shortened　by　51.6　%,　and　the　biomass　increases　from　0.06　g/L　to　3.94　g/L.　In　addition,　the　removal　rate　of　NH4+-N　increased　by　106.0　%　to　1.56　mg　L−1　h−1.　This　work　provides　a　feasible　method　for　optimizing　the　design　and　operational　parameters　of　PBR　aiming　the　engineering　application.　©　2024　Elsevier　Ltd