Rhenium-tungsten　core-shell　powder　was　prepared　by　solid-liquid　mixing　method　and　then　osmium　powder　was　added　to　prepare　ternary　mixed　powder　with　special　coating　structure　after　pretreatment.　After　the　powder　was　pressed,　sintered,　impregnated　with　salt,　washed　and　annealed,　a　ternary　mixed-base　cathode　of　tungsten-rhenium　osmium　was　prepared.　After　impregnation　with　411　salt,　the　pulse　emission　test　found　that　W2Re1Os1　cathode　which　is　a　ternary　mixed-base　cathode　has　the　best　electron　emission　performance　and　the　current　emission　density　can　reach　35　A/cm2　at　1050　℃,　which　is　slightly　higher　than　that　of　the　same　type　of　binary　mixed-base　cathode,　and　which　reaches　the　level　of　the　ternary　film　cathode　covered　with　tungsten,　rhenium　and　osmium.　It　is　verified　by　experiments　that　neither　Re　nor　Os　reacts　with　the　active　salt　during　the　impregnation　process　of　the　ternary　tungsten-rhenium-osmium　mixed-base　cathode,　and　the　active　substance　is　produced　by　the　reaction　of　W　and　the　active　salt.　©　2024　Science　Press.　All　rights　reserved.