In　this　study,　CoCrNi　MEAs　added　with　different　silicon　contents　(0,　0.1,　0.2　for　molar　ratio)　were　prepared　by　arc　melting.　The　cold　rolled　and　annealed　microstructural　evolution　and　tensile　mechanical　behavior　of　the　alloys　were　systematically　investigated.　The　results　show　that　the　distribution　of　elements　in　the　alloys　after　homogenization　annealing　is　uniform.　As　the　rolling　reduction　increased　from　20%　to　60%,　SEM-BSE　characterization　showed　that　the　deformed　microstructure　of　the　alloys　transformed　from　neatly　aligned　slip　bands　to　tangled　shear　bands.　TEM　characterizations　show　that　the　alloys　have　typical　cold　rolling-induced　microbands,　dislocation　cells,　and　high-density　dislocation　walls　caused　by　plane　slip　after　cold　rolling　for　60%.　Also,　these　deformed　microstructures　are　finer　in　size　concerning　silicon-alloyed　MEAs　compared　to　silicon-free　MEAs.　After　annealing　at　650　degrees　C　for　60　min,　the　deformed　microstructure　was　replaced　by　a　heterogeneous　grain　structure　composed　of　ultrafine　grains,　micron-scale　grains,　high-density　dislocation　regions,　and　residual　deformation　regions.　With　the　increase　of　Si　content,　the　yield　strength　and　tensile　strength　increased　with　the　change　of　the　heterogeneous　grain　structure.　The　tensile　strength　of　the　Si0.2　MEAs　even　exceeds　1.5　GPa,　and　still　maintains　a　uniform　elongation　greater　than　20%　at　77　K.　The　evolution　of　the　cold-rolled　microstructure　of　silicon　alloyed　MEAs　are　mainly　related　to　the　reduction　of　stacking　fault　energy　and　a　strong　dependence　on　grain　orientation　and　applied　stress　direction.　The　formation　of　nano-DTs　and　HCP　phases　resulted　in　the　excellent　combination　of　strength　and　ductility　at　77　K.　The　typical　heterogeneous　grain　structure　realizes　the　strength-ductility　synergy　of　the　alloys.