In order to study the corrosion behavior of the new combination form of “316L stainless steel cladded rebar and seawater sea-sand concrete” in simulated seawater, 316L stainless steel cladded rebar is taken as the research object, and its natural passivation behavior in concrete pore simulation solution is studied by using the open-circuit potential test, electrochemical impedance spectroscopy test and linear polarization curve test. And cast it in seawater sea-sand concrete to study its corrosion behavior in simulated seawater. The results show that 316L stainless steel cladded rebar can complete passivation in the concrete pore simulation solution, the total resistance Rt after immersion for 240 h is 8.26 MΩ·cm2, the corrosion rate is 0.0016 μA/cm2, the passivation effect is perfect; 316L stainless steel cladded rebar seawater sea-sand concrete specimen corrosion resistance in 3.5 wt.% NaCl solution with the increase in the immersion age of immersion and then remains stable, and the corrosion current density of the specimen after 140 d of immersion is 1.21 μA/cm2, which still maintains a high corrosion resistance.