The　shuttle　effect　of　lithium　polysulfides　(LiPS)　and　sluggish　redox　kinetic　still　restrict　the　commercial　application　of　lithium-sulfur　batteries　(LSBs).　Developing　the　modified　functional　separators　that　block　the　migration　of　LiPS　and　accelerate　the　LiPS　conversion　is　an　effective　method　to　solve　both　problems.　Here　we　report　a　MoSe2@g-C3N4　composite　material　with　the　merits　of　strong　adsorption　in　g-C3N4　and　appropriate　migration　in　MoSe2　for　LiPS　simultaneously　achieved　on　the　surface.　g-C3N4　has　strong　adsorption　for　LiPS　while　MoSe2　with　a　low　migration　barrier　of　LiPS　and　improves　their　conversion　into　solid-state　Li2S.　The　excellent　wettability　of　MoSe2@g-C3N4　facilitates　electrolyte　migration　and　improves　the　electrochemical　performance.　With　a　MoSe2@g-C3N4　interlayer　delivered　2.2　times　increase　initial　capacity　than　that　with　a　conventional　polypropylene　(PP)　separator　at　0.5C,　and　a　low-capacity　decay　per　cycle　of　0.09　%　was　achieved　at　0.5C　after　500　cycles.　It　showed　the　best　rate　capability　of　564.2　mA　h　g−1　at　3C.　Even　under　the　high　sulfur　loadings　of　3.2　and　4.0　mg　cm−2,　showing　high　initial　capacity　and　decent　capacity　retention.　This　project　provides　a　novel　insight　into　designing　the　functional　separators　with　the　g-C3N4　substrate　composites　for　stable　LSBs.　©　2022　Elsevier　B.V.