The　start-up　of　the　aerobic　granular　sludge　(AGS)　process　under　low　temperature　is　challenging.　In　this　study,　the　sequencing　batch　reactor　(SBR)　was　fed　with　synthetic　wastewater　and　the　temperature　was　controlled　at　15　celcius.　The　main　components　in　the　synthetic　wastewater　were　sodium　acetate　and　ammonium　chloride.　The　influent　chemical　oxygen　demand　(COD)　and　NH4+-N　concentrations　were　300　and　60　mg/L,　respectively.　The　AGS　was　successfully　cultivated　in　60　days　by　gradually　shortening　the　settling　time.　During　the　stable　operation　stage　(61-100　d),　the　average　effluent　COD,　NH4+-N,　NO2--N,　and　NO3--N　concentrations　were　47.2,　1.0,　47.2,　and　5.1　mg/L,　respectively.　Meanwhile,　the　nitrite　accumulation　rate　(NAR)　reached　90.6%.　Batch　test　showed　that　the　smaller　AGS　had　higher　NH4+-N　removal　rate　while　the　larger　AGS　performed　higher　NAR.　The　NH4+-N　removal　rates　of　R1　(1.0-2.0　mm),　R2　(2.0-3.0　mm),　and　R3　(＞3　mm)　granules　were　0.85,　0.61,　and　0.45　g　N/(kg　VSS　center　dot　h),　respectively.　Meanwhile,　the　NAR　of　R1,　R2,　and　R3　were　36.2%,　77.2%,　and　94.9%,　respectively.　The　obtained　results　could　provide　important　guidance　for　the　cultivation　of　AGS　in　low-temperature　wastewater　treatment.