The　lamellar　graphitic　carbon　nitride　(g-C3N4)　membranes　with　controllable　interlayer　thickness　could　have　promising　separation　performance　for　desalination.　Understanding　the　molecular　basis　of　the　transport　behavior　of　water　and　ions　through　well-defined　g-C3N4　nanochannels　is　essential　for　the　design　of　novel　desalination　membranes.　Herein,　we　performed　non-equilibrium　molecular　dynamics　(MD)　simulations　to　investigate　the　transport　mechanisms　of　water　molecules　and　ions　through　g-C3N4　nanochannels　with　various　thicknesses.　The　confinement　effect　of　the　nanochannel　could　impact　the　water　density　distribution　between　the　g-C3N4　nanosheets.　Meanwhile,　owing　to　the　strong　adsorption　effect　of　g-C3N4　nanosheets,　the　interfacial　water　layer　and　the　middle　water　layer　in　nanochannels　featured　with　distinct　transport　behaviors.　This　water　conduction　behavior　is　different　from　that　of　graphene　nanochannels.　For　desalination,　the　MD　simulations　showed　that　the　g-C3N4　nanochannel　could　entirely　reject　the　ions　when　the　channel　thickness　was　smaller　than　1.0　nm.　Additionally,　the　migration　behavior　of　hydrated　ions　was　correlated　with　the　water　structures　in　g-C3N4　nanochannels.　This　work　not　only　improved　the　understanding　of　the　molecular　transport　mechanism　of　water　molecules　and　ions　in　the　g-C3N4　nanochannel,　but　also　provided　useful　guidelines　for　designing　next-generation　desalination　membranes.　©　2023　Elsevier　B.V.