Abstract: In view of the fact that the building structure in the salt lake area is subjected to the double damage of harsh climate environment and corrosive ions, which leads to the phenomenon of shortened life. Magnesium cement recycled fine aggregate reinforced concrete was used to slow down the life degradation speed of the structure. The galvanostatic accelerated test was carried out by adding different amounts of regenerated fine aggregate and burying it in saline soil. With the help of electrochemical workstation, ultrasonic non-destructive testing technology, SEM and XRD, the evolution mechanism of microstructure was analyzed, Finally, the degradation process of the two-parameter Weibull distribution function was introduced to evaluate the reliability of the evaluation index corrosion current density icorr and relative dynamic elastic modulus modeling. The results show that: When mixed with mass ratios of 15%, 30% and 45% fine aggregates in the accelerated test environment, aggressive ions such as Cl⁻, CO₃ ²⁻ and SO₄ ²⁻ invade the interior of the specimen with the increase of the content of recycled fine aggregates. The probability increases, and the degree of damage to the internal structure is more significant. The large and block corrosion products gradually loosen, which makes the internal structure deteriorate further. The specimens with 15% and 30% dosage have low corrosion degree, and the specimen with 45% dosage is in serious corrosion. The dynamic elastic modulus is used as the degradation parameter to obtain 15%, 30%, 45% regeneration. The service life of the samples with fine aggregate content is 10000 days, 7500 days and 6000 days, respectively. The working life of the specimen with 45% dosage obtained by the corrosion current density i_corr is 4000 days. The corrosion current density durability degradation of steel bars is more sensitive to the dynamic elastic modulus, which has considerable guiding significance for the daily maintenance and inspection of magnesium cement recycled fine aggregate reinforced concrete components.