Asymmetric　composite　membranes　composed　of　a　porous　support　layer　and　compact　selective　layer　have　been　used　in　many　fields.　Nowadays,　most　studies　focus　on　the　material　design　and　structure　optimization　of　the　selective　layer.　However,　nano-confined　pores　in　the　porous　support　layer　can　also　be　used　to　construct　a　composite　membrane　with　unique　architecture.　The　functional　polymer　and　nanoporous　particles　can　be　embedded　in　the　pores　rather　than　on　the　support　surface　to　form　a　composite　membrane,　which　can　solve　some　significant　problems,　such　as　the　contradiction　between　integrity　and　ultrathin　thickness　of　the　selective　layer,　the　interfacial　adhesion　between　selective　layer　and　support　layer,　and　the　orientation　of　the　selective　layer.　The　separation　performance　and　the　stability　of　the　composite　membranes　are　thus　improved.　Summarized　in　this　review　are　the　latest　studies　on　the　formation　of　composite　membranes　using　confined　space　of　porous　support　layer　which　are　defined　as　a　nano-confined　composite　membrane　in　this　review,　with　the　focus　on　membrane　structure,　pore　property,　and　fabrication　strategy.　The　summary　and　outlook　are　discussed　with　a　perspective　on　high-performance　composite　membranes.　©　The　Author(s)