Increasing　the　service　temperature　of　TiAl　intermetallics　is　the　main　challenge　for　the　development　of　next-generation　aircraft.　Dispersion-strengthening,　an　effective　means　to　further　improve　the　high-temperature　performance　of　metals,　fails　to　implement　in　TiAl　intermetallics　due　to　difficulties　in　interface　optimization.　Here,　we　successively　fabricate　a　TiAl　naocomposite　with　fully　lamellar　microstructures　and　homogeneously　dispersed　Ti2AlC　nanoprecipitates　via　spark　plasma　sintering.　The　composite　consisted　of　semicoherent　interfaces　among　gamma-TiAl/Ti2AlC　precipitates/alpha(2)-Ti3Al,　in　addition　to　continuous　polysynthetic　nanotwins.　Strong　pinning　effects　as　well　as　strain-induced　nanoscale　TiCr2　precipitation　uplift　the　operation　temperature　of　TiAl　nanocomposites　by　more　than　50　degrees　C.　Furthermore,　we　experimentally　proved　that　semicoherent　interfaces　among　in　situ　Ti2AlC　precipitates　and　its　surrounding　matrix　serve　as　oxygen　diffusion　barrier　during　isothermal　oxidization　and　significantly　drop　down　the　mass　gain　of　TiAl　nanocomposites　during　operation,　making　the　present　nanocomposite　a　highly　potential　candidate　for　use　as　light-weight　structural　materials　in　automotive　and　aerospace　industries.