Aiming　at　deepening　the　understanding　of　the　formation　and　evolution　of　emerging　microalgal-bacterial　granule　(MBG)-based　wastewater　treatment　systems,　the　recent　advances　regarding　the　formation　processes,　transfer　phenomena,　innovative　bioreactors　development　and　wastewater　treatment　performance　of　MBG-based　systems　are　comprehensively　reviewed　in　this　work.　Particularly,　the　successful　establishments　of　MBG-based　systems　with　various　inocula　are　summarized.　Besides,　as　the　indispensable　factors　for　biochemical　reactions　in　MBGs,　the　light　and　substrates　(organic　matters,　inorganic　nutrients,　etc)　need　to　undergo　complicated　and　multi-scale　transfer　processes　before　being　assimilated　by　microorganisms　within　MBGs.　Therefore,　the　involved　transfer　phenomena　and　mechanisms　in　MBG-based　bioreactors　are　critically　discussed.　Subsequently,　some　recent　advances　of　MBG-based　bioreactors,　the　application　of　MBG-based　systems　in　treating　various　synthetic　and　real　wastewater,　and　the　future　development　directions　are　discussed.　In　short,　this　review　helps　in　promoting　the　development　of　MBG-based　systems　by　presenting　current　research　status　and　future　perspectives.　©　2022