Based　on　representative　concrete　design　mixes　used　in　the　domestic　railway　project,　the　concrete＇s　chloride-ion　penetration　is　studied　and　its　influencing　factors　are　also　analyzed.　Results　show　that　concrete　curing　age,　type,　and　volume　of　mineral　admixtures　are　the　main　influencing　factors　of　concrete＇s　chloride　ion　penetration.　With　the　concrete　curing　age　extending,　the　chloride-ion　penetration　value　lowers　and　it　is　reasonable　to　evaluate　test　results　through　curing　age　of　56　days.　Adding　the　volume　of　fly　ash　and　ground　granulated　blast　furnace　slag(GGBS),　the　chloride-ion　penetration　value　declines.　The　effect　of　reducing　concrete＇s　chloride　ion　penetration　of　fly　ash　is　much　better　than　that　of　GGBS,　and　both　effects　are　almost　equal　when　the　volume　reaches　40%.　Other　concrete　mixed　parameters,　such　as　water　binder　ratio,　air　content,　and　types　of　cement　and　super　plasticizers　are　less　important　influencing　factors.