The　coupling　between　the　multilayer　interfaces　in　compound　jets　has　notable　effects　on　the　structure　and　generation　sequence　of　the　formed　double　emulsions.　These　effects　are　important　for　the　performance　of　double　emulsions,　such　as　the　capacity,　release　rate,　and　controlled　release　threshold　in　medical　and　chemical　applications.　In　this　work,　the　influence　of　the　inner　droplet　on　the　necking　of　compound　jets　is　investigated　in　a　horizontally　placed　capillary　flow-focusing　device　based　on　microfluidics.　Three　types　of　interface　coupling　modes　are　explored.　Scaling　laws　that　describe　the　time　evolution　of　the　neck　radius　for　these　different　coupling　modes　are　analyzed,　and　the　reasons　for　transitions　between　such　scaling　laws　are　discussed.　The　results　show　that　the　motion　and　deformation　of　the　droplet　have　a　large　impact　on　the　neck　breakup　in　the　inertial　regime,　causing　the　scaling　law　to　change,　but　only　a　slight　effect　in　the　viscous　regime.　Moreover,　the　inner　droplet　can　prevent　the　jet　from　breaking　up　owing　to　interface　coupling.　These　findings　could　help　us　to　understand　the　role　of　interface　coupling　in　compound　jets　and　provide　a　reference　for　controlling　the　generation　of　compound　droplets.　©　2021　Author(s).