Ultra-high　performance　concrete　(UHPC)　was　prepared　via　mixing　water　containing　different　chloride　salts　(i.e.,　NaCl,　CaCl2　and　MgCl2).　The　electrochemical　indexes　of　the　internal　reinforcement　during　passivation　period　were　measured　by　linear　polarization,　electrochemical　impedance　spectroscopy　and　cyclic　polarization.　The　passivation　behavior　and　evolution　of　steel　bars　in　UHPC　under　the　coupling　action　of　different　chloride　salts　were　investigated.　The　results　show　that　the　reinforcement　in　UHPC　is　able　to　be　passivated　under　three　different　chloride　salt　systems.　The　resistances　of　UHPC　matrix,　steel　passivation　film　and　steel　charge　transfer　increase　continuously　with　the　hydration　age.　At　the　same　concentration　of　Cl–　ions,　the　introduction　of　Ca　salts　increases　the　possibility　of　steel　corrosion　to　a　certain　extent,　while　the　introduction　of　Mg　salts　delays　the　corrosion　process　of　steel　bars　to　some　extent.　The　pitting　corrosion　sensitivity　of　reinforcement　increases　with　the　increment　of　Cl–　ions　concentration.　At　a　high　Cl–　ions　concentration,　the　pitting　sensitivity　of　steel　bars　in　Na–Ca　system　is　greater　than　that　in　Na–Mg　system.　©　2023　Chinese　Ceramic　Society.　All　rights　reserved.