The　removal　of　nutrients　in　sewage　treatment　plants　can　be　significantly　impacted　by　carbon　limitations,　especially　for　treating　low　carbon　to　nitrogen　ratio　(C/N)　wastewater,　which　can　markedly　increase　operational　costs.　Simultaneous　nitrification,　endogenous　denitrification,　and　phosphorus　removal　combined　with　aerobic　granular　sludge　(SNEDPR-AGS)　has　emerged　as　one　of　the　optimal　processes　for　treating　low　C/N　wastewater　owing　to　its　high　carbon　utilization　efficiency;　however,　the　long-term　effect　of　microplastics　(MPs)　on　this　system　remains　unclear.　This　study　investigated　the　granular　effect　and　microbial　response　of　an　SNEDPR-AGS　system　for　treating　low　C/N　wastewater　under　long-term　exposure　(180　d)　to　polyethylene　terephthalate　microplastics　(PET-MPs).　The　results　showed　that　the　integrity　of　the　AGS　structure　was　disrupted　significantly　as　the　PET-MP　concentration　increased,　with　clear　AGS　cracks　appearing　on　days　180,　124,　and　74　after　exposure　to　1,　10,　and　100　mg/L　of　PET-MPs,　respectively.　Additionally,　the　addition　of　PET-MPs　also　inhibited　denitrification　and　phosphorus　removal　due　to　a　decrease　in　the　relative　abundance　of　functional　genes　(napAB,　nirK/　nirS,　ppk1,　ppk2,　and　ppx).　Notably,　both　chemometric　and　high-throughput　sequencing　results　indicated　that　the　metabolic　form　of　the　system　would　shift　from　a　polyphosphate-accumulating　metabolism　to　a　glycogenaccumulating　metabolism.　The　reason　may　be　that　PET-MP　stress　inhibited　the　relative　abundance　of　func