The　carbon-doped　Fe50Mn30Co10Cr10　HEAs　with　excellent　cryogenic　mechanical　properties　were　prepared　by　powder　metallurgy,　and　their　tensile　deformation　behavior　and　strain-hardening　mechanism　were　investigated.　The　yield　strength　of　the　HEAs　at　77　K　improved　from　489.7　to　1087.0　MPa　as　the　carbon　content　increased　from　0　to　3　at.　%,　which　mainly　stems　from　the　increased　lattice　friction　caused　by　the　addition　of　carbon　and　the　cryogenic　environment;　the　ultimate　tensile　strength　of　the　HEAs　doped　with　2　and　3　at.　%　carbon　reached　1.2　and　1.4　GPa,　respectively,　while　the　elongation　to　fracture　reached　31.6　%　and　16.8　%,　respectively,　which　is　mainly　attributed　to　the　joint　activation　of　microbands,　twinning,　and　HCP　phase.　The　deformation　mechanism　gradually　changed　from　deformation-induced　phase　transformation　to　microbands　and　twinning　with　increasing　carbon　content　under　cryogenic　conditions.　This　study　provides　a　meaningful　reference　for　the　design　and　development　of　powder　metallurgy　HEAs　with　excellent　performance　in　cryogenic　applications.(c)　2023　The　Authors.　Published　by　Elsevier　B.V.　This　is　an　open　access　article　under　the　CC　BY-NC-ND　license　(http://creativecommons.org/licenses/by-nc-nd/4.0/).