Metal-organic　frameworks　(MOFs)　are　highly　versatile　materials　that　have　been　identified　as　promising　candidates　for　membrane-based　gas　separation　applications　due　to　their　uniformly　narrow　pore　windows　and　virtually　unlimited　structural　and　chemical　features.　Defect　engineering　of　MOFs　has　opened　new　opportunities　for　manipulating　MOF　structures,　providing　a　simple　yet　efficient　approach　for　enhancing　membrane　separation.　However,　the　utilization　of　this　strategy　to　tailor　membrane　microstructures　and　enhance　separation　performance　is　still　in　its　infancy.　Thus,　this　summary　aims　to　provide　a　guideline　for　tailoring　defective　MOF-based　membranes.　Recent　developments　in　defect　engineering　of　MOF-based　membranes　will　be　discussed,　including　the　synthesis　strategies　for　defective　MOFs,　the　effects　of　defects　on　the　gas　adsorption　properties,　gas　transport　mechanisms,　and　recently　reported　defective　MOF-based　membranes.　Furthermore,　the　emerging　challenges　and　future　prospects　will　be　outlined.　Overall,　defect　engineering　offers　an　exciting　opportunity　to　improve　the　performance　of　MOF-based　gas　membranes.　However,　there　is　still　a　long　way　to　go　to　fully　understand　the　influence　of　defects　on　MOF　properties　and　optimize　the　design　of　MOF-based　membranes　for　specific　gas　separation　applications.　Nonetheless,　continued　research　in　this　field　holds　great　promise　for　the　development　of　next-generation　membrane-based　gas　separation　technologies.