Efficient　start-up,　cultivation　and　maintenance　of　aerobic　granular　sludge　(AGS)　in　continuous　flow　reactors　(CFRs)　is　critical　for　its　full-scale　application　in　wastewater　treatment　plants　(WWTPs).　The　successful　implementation　of　AGS　under　continuous　flow　condition　depends　on　the　configuration　of　CFR　that　provides　the　selective　pressures　and　hydraulic　shear　force　(HSF)　to　sludge　required　for　rapid　granulation.　Important　progress　has　been　witnessed　with　respect　to　CFR　configurations　in　recent　decades　for　in-situ　granulation　of　aerobic　sludge.　This　review　summarized　the　difficulties　of　granulation　during　continuous　flow,　as　well　as　the　reactor　configuration,　granulation　mechanism　and　the　AGS　characteristics,　along　with　the　future　research　prospects.　It　is　of　significance　to　promote　the　innovation　of　continuous　flow　configuration　in　order　to　realize　the　AGS　application　in　mainstream　WWTPs　in　the　future.　(c)　2021　Society　of　Chemical　Industry　(SCI).