This　paper　presents　a　prefabricated　internal　support　system　for　deep　foundation　pit　engineering　in　subway　open　cut　stations,　which　is　developed　based　on　the　merits　and　demerits　of　concrete　supports　and　steel　supports.　The　system　consists　of　Prefabricated　Multi-limb　Concrete-Filled　Steel　Tube　(PM-CFST)　support　segments　and　Moldbag　Concrete　Clamped　Joints　(MCCJ).　Among　them,　this　paper　delves　into　the　MCCJ,　which　serves　as　a　pivotal　force　for　transmission　and　bearing　within　the　system.　The　design　scheme,　structural　characteristics,　and　working　principle　of　the　MCCJs　are　comprehensively　elucidated,　showcasing　the　potential　of　the　MCCJ　to　enhance　end　node　stiffness　and　strength　while　achieving　secure　end　fixed　connections.　The　bearing　performance　of　the　MCCJs　was　further　investigated　by　designing　and　processing　three　specimens　for　uniaxial　compression　load　tests.　The　resulting　load-displacement　curves,　load-strain　curves,　and　failure　modes　were　subsequently　analyzed.　The　test　results　demonstrate　that　MCCJ　exhibits　a　favorable　compressive　load　capacity　exceeding　5000　kN　and　possesses　excellent　ductility.　Subsequently,　finite　element　models　were　established　using　ABAQUS　software　for　numerical　calculations,　which　were　then　compared　with　experimental　results　to　verify　their　consistency.　Moreover,　parameter　research　was　conducted　to　investigate　the　influence　of　factors　such　as　the　strength　grade　of　concrete　inside　the　steel　tube　and　mold-bag　on　the　yield　load　and　initial　compressive　stiffness　of　MCCJs.　By　analyzing　load-strain　curves　obtained　from　experimental　measurements　and　conducting　quantitative　numerical　simulation　research,　this　study　investigates　the　deformation　characteristics　and　parameter　influence　laws　of　MCCJs.