To　improve　the　mechanical　properties　of　Fe50Mn30Co10Cr10　high　entropy　alloy　(HEA),　a　series　of　carbon-containing　HEAs　based　on　Fe50Mn30Co10Cr10　were　successfully　prepared　by　powder　metallurgy.　The　effects　of　carbon　content　on　microstructural　evolution　and　mechanical　properties　of　the　as-sintered　HEAs　were　investigated.　The　improved　FCC　phase　stability　and　the　decreased　ς3　twin　grain　boundary　proportion　as　the　increase　of　carbon　content　are　mainly　due　to　the　increased　stacking　fault　energy.　As　the　carbon　content　increases,　the　phase　structure　of　the　as-sintered　HEAs　changes　from　FCC　+　HCP　phases　to　FCC　phase　and　then　to　FCC　+　M23C6　phases,　and　the　deformation-induced　martensitic　transformation　from　FCC　to　HCP　weaken　gradually.　The　solid　solubility　of　carbon　in　the　as-sintered　Fe50Mn30Co10Cr10　HEAs　is　below　2　at.%.　A　large　number　of　carbides　can　be　observed　in　the　microstructure　of　the　alloys　at　higher　carbon　content.　The　yield　strength　of　the　alloys　increases　approximately　linearly　with　carbon　content,　while　the　uniform　elongation　first　increases　and　then　decreases.　The　(Fe50Mn30Co10Cr10)98C2　HEAs　with　nano-carbides　and　ultrafine　manganese　oxide　exhibited　a　yield　strength　of　362　MPa,　an　ultimate　tensile　strength　of　792　MPa,　and　uniform　elongation　of　36.7%,　showing　simultaneous　improvement　in　strength　and　ductility　compared　with　the　carbon-free　alloy.　This　is　due　to　the　joint　contribution　of　multiple　strengthening　mechanisms　in　the　carbon-containing　HEA.　Interstitial　solid　solution　strengthening　and　grain　boundary　strengthening　act　as　the　dominant　strengthening　mechanism.　Alloying　with　carbon　element　is　a　feasible　method　to　enhance　the　mechanical　properties　of　HEAs　prepared　by　powder　metallurgy.　©　2022　The　Author(s).