This　paper　investigated　chloride-corroded　concrete-encased　steel　(CES)　slender　columns　subjected　to　axial　loading.　Twelve　specimens　were　tested　to　evaluate　the　effects　of　corrosion　on　failure　modes　and　mechanical　performance.　Results　show　that　chloride　corrosion　accelerates　structural　degradation　and　shifts　failure　from　end-region　to　mid-span　as　corrosion　intensifies.　Higher　slenderness　ratios　amplify　corrosion-induced　losses　in　load-bearing　capacity　and　stiffness.　Based　on　the　test　data,　a　predictive　formula　was　proposed　to　estimate　axial　load　capacity　considering　section　loss　and　confinement　effects.　Stability　analysis　using　a　modified　Euler　approach　indicated　no　instability　failure　but　revealed　a　reduced　safety　margin　with　increasing　corrosion　severity　and　slenderness.　A　validated　finite　element　model　was　developed,　and　parametric　analysis　showed　that　CES　columns　experience　significant　stiffness　and　stability　deterioration　when　the　slenderness　ratio　exceeds　62.　The　findings　support　structural　assessment　and　maintenance　planning　for　CES　members　in　corrosive　environments.