Metal-organic framework (MOF) membranes hold great promise in energy-efficient chemical separa-tions.The outstanding challenges of the microstructural design stem from (1) thinning of membranes to immensely reduce the mass-transfer resistance (for high permeances);(2) tuning of orientation to optimize the selective transport of gas molecules,and (3) reinforcement of intercrystalline structure to subside leakage through defective gaps (for high selectivity).Here,we propose the ZIF-L membrane that is completely confined into the voids of the alumina support through an interfacial assembly process,producing an appealing membrane-interlocked-support (MIS) composite architecture that meets the requirements of the microstructural design of MOF membranes.Consequently,the membranes show average H2 permeances of above 4000 GPU and H2/CO2 separation factor (SF) of above 200,representing record-high separation performances of ZIF-L membranes and falling into the industrial target zone (H2 permeance ＞ 1000 GPU and H2/CO2 SF ＞ 60).Furthermore,the ZIF-L membrane possessing the MIS com-posite architecture that is established with alumina particles as scaffolds shows mechanical stability,scraped repeatedly by a piece of silicon rubber causing no selectivity loss.