In order to improve the salt spray corrosion resistance of steel structure in seaside construction, reinforced concrete is used to design steel structure in seaside construction. Based on the analysis of yield strain characteristics, an automatic monitoring method of salt spray corrosion of steel structure in seaside construction is put forward, and the prestress characteristic analysis model of reinforced concrete is established. The characteristic parameter estimation method of shear capacity is used to analyze the salt fog corrosion resistance of steel structure concrete in seaside building construction, and the vertical deflection characteristic quantity of steel structure in seaside construction is extracted. through the method of steel bar strain measurement and plate angle binding measurement, the tensile force test of reinforced concrete is carried out, and the strain difference of steel structure in seaside construction is analyzed quantitatively. Under the dual action of steel and concrete, the salt spray corrosion resistance of steel structure in seaside construction is improved. The test results show that the salt fog corrosion resistance of steel structure design in seaside building construction is better, the yield strain ability of reinforced concrete is enhanced, and the resistance stiffness of steel structure in seaside building construction is improved.