The　metal-free　graphitic　carbon　nitride　(g-C3N4)　with　a　series　of　merits　like　low　cost,　favorable　stability,　and　controllable　two-dimensional　graphite-like　structure,　has　been　extensively　studied　for　photocatalytic　H2　evolution.　Composite　engineering　is　regarded　as　one　of　effective　strategies　to　adjust　the　kinetics　of　photogenerated　carriers　in　g-C3N4　for　elevating　its　photocatalytic　performance.　Herein,　the　composite　system　of　g-C3N4　with　oxynitride　LaTiO2N　was　elaborately　constructed　for　improving　photocatalytic　H2-evolution　performance.　With　systematical　characterizations,　the　partial　cover　of　g-C3N4　nanosheets　on　LaTiO2N　(LaTiO2N@g-C3N4)　was　verified　and　promoted　the　sufficient　contact　between　g-C3N4　and　LaTiO2N,　accompanied　by　the　formation　of　the　(oxy)nitride　heterojunction.　Benefited　by　the　well-matched　band　structures　for　g-C3N4　and　LaTiO2N,　the　(oxy)nitride　heterojunction　strengthened　the　separation　of　photogenerated　carriers　and　therefore　enhanced　the　photocatalytic　performance　of　g-C3N4.　This　work　gives　more　insight　in　composite　engineering　on　g-C3N4,　and　also　provides　feasible　guidelines　for　designing　g-C3N4-based　photocatalysts　towards　improving　photocatalytic　performance.　©　2022　Elsevier　B.V.