Seawater and sea sand mixed in concrete will cause rebar of structural concrete corrosion, referring to the principles of composition and design of MCI and Pearson’s Hard-Soft Acid-Base (HSAB) theory, as well as to synergy effect of corrosion inhibitor applied in chemical industry, compound corrosion inhibitor has been designed consisting of diisopropanolamine, surface active agent, inorganic salts and so on. This paper research the relation between polarization potential and time of rebar in seawater-and-sea sand concrete through a series of experiments by adding corrosion inhibitor into seawater-and-sea sand concrete to improve its corrosive resistance characteristics. The results indicate that Z5 has the best inhibition effect. Corrosion inhibitor Z5 comprises 50% of triethanolamine, 20% of dimethylethanolamine (DMEA), 25% of triethoxysilane and 5%lithium nitrate, and its proper content applied in seawater-and-sea sand concrete is 1.5%. Rebar have been embedded in seawater-and-sea sand concrete for the long-term test. The results show that corrosion resistance performance of seawater-and-sea sand concrete with corrosion inhibitor Z5 was significantly improved, and the embedded bar was not corroded at all within 420 days.