The　excellent　combination　of　strength　and　plasticity　of　heterostructures　high-entropy　alloys　(HEAs)　has　attracted　much　attention,　but　it　is　only　impossible　to　achieve　further　engineering　applications.　Therefore,　the　corrosion　resistance　of　FeCoCrNiMn　HEAs　with　different　heterogeneous　grain　structures　(HGS)　and　Si　contents　in　sodium　chloride　solution　was　studied　in　this　paper.　Experimental　results　revealed　that　except　for　Si-free　alloy,　pitting　corrosion　occurred　in　other　alloys.　Moreover,　with　the　increase　of　volume　fraction　and　Si　content　in　the　residual　deformed　grain　region,　the　pitting　corrosion　gradually　increases.　Si　improves　the　self-corrosion　resistance　of　the　alloy.　The　p-n　heterojunctions　are　observed　in　all　HEAs.　The　thickness　or　composition　of　the　passivation　film　can　be　changed　by　changing　the　composition　of　the　alloy　structure　or　adding　Si.　The　high　activity　of　the　residual　deformed　grain　region　in　the　heterogeneous　grain　structure　HEAs　makes　it　preferentially　undergo　anodic　reaction　and　be　eroded　by　chloride　ions.　Si　promotes　the　diffusion　of　metal　elements　and　accelerates　the　pitting　reaction.　This　study　establishes　the　correlation　between　heterogeneous　grain　structure　and　corrosion　behavior,　and　provides　insights　for　the　design　of　high-entropy　alloys　with　excellent　comprehensive　properties.　©　2025　Elsevier　B.V.