With　the　increasing　demands　for　communications　in　the　remote　areas　without　terrestrial　networks,　satellite　networks　have　become　a　promising　paradigm.　However,　it　is　an　issue　of　satisfying　demands　with　limited　resources　of　satellites.　In　this　paper,　considering　a　NOMA-enabled　satellite-terrestrial　network,　we　propose　a　resource　allocation　strategy　to　maximize　spectral　efficiency　of　satellites.　Firstly,　we　formulate　the　optimization　problem　as　a　mixed　integer　nonlinear　problem.　Due　to　its　non-convexity,　we　transform　the　non-convex　problem　into　three　subproblems.　Then,　we　propose　subcarrier　allocation　algorithm　and　Lagrange　quick　iterative　water　filling　algorithm　with　low　complexity　to　solve　the　subproblems.　Finally,　the　numerical　results　demonstrate　that　the　proposed　low-complexity　scheme　is　close　to　the　optimal　solution　obtained　by　the　exhaustive　algorithm.　©　2022　IEEE.