Ultra-high　performance　concrete　(UHPC)　and　common　mortar　were　prepared　using　simulated　sea　sand　at　different　chloride　ion　contents.　The　electrochemical　indexes　of　the　internal　reinforcement　during　passivation　period　were　measured　by　linear　polarization　resistance　(LPR),　electrochemical　impedance　spectroscopy　(EIS)　and　cyclic　polarization.　The　passivation　evolution　of　reinforcement　and　the　effect　of　chloride　ion　on　the　growth　of　passivation　film　were　investigated,　and　the　passivation　behavior　difference　between　UHPC　and　ordinary　mortar　was　compared.　The　experiment　results　show　that　the　corrosion　rate　of　reinforcement　in　UHPC　decreases　with　the　increase　of　age.　The　corrosion　rate　is　accelerated,　but　its　effect　is　limited,　and　it　has　no　effect　on　the　density　of　passive　film　when　chloride　ion　content　in　sea　sand　is　increased.　When　the　content　of　chloride　ion　in　the　sea　sand　is　below　0.448%,　the　steel　bars　could　be　passivated　within　10　d,　and　the　corrosion　rate　is　the　similar　after　passivation.　©　2020,　Editorial　Department　of　Journal　of　the　Chinese　Ceramic　Society.　All　right　reserved.