The　microstructure　and　oxidation　properties　from　bulk　material　to　atomic　scale　of　NiCr　alloys　with　different　Cr　contents　from　10　to　50　at%　were　systematically　studied.　The　oxidation　mechanism　in　NiCr　alloys　with　different　Cr　contents　was　analysed　by　in-situ　environmental　transmission　electron　microscopy.　The　increased　porosity　of　the　NiO/NiCr2O4　oxide　layer　in　the　10　at%　Cr-containing　alloy　seriously　decreases　its　oxidation　resistance,　and　Cr　contents　between　20　and　40　at%　offer　outstanding　oxidation　resistance　due　to　the　inhibited　growth　of　NiO/　NiCr2O4　oxides.　Ni-50　at%Cr　alloy　exhibit　poor　corrosion　resistance　due　to　short-circuit　oxidation　paths　by　its　FCC/BCC　dual-phase　structure.