According to the corrosion ions in groundwater and soil of the platform along Lanzhou Metro, four kinds of coupling salt solutions containing SO4^2-, Cl^-, Mg²⁺ were allocated. The reinforced concrete specimens were placed in the coupling salt solution every 90 days to conduct non-destructive testing by electrochemical workstation, and non-monotonic Wiener degradation process was selected to carry out according to the width of cracks. Combining with failure criterion, failure threshold was obtained and durability reliability model was established. The results show that ：Under the coupled salt solution environment, the polarization curve moves towards the direction of increasing corrosion current density and negative potential. The ac impedance spectrum shows a double capacitive reactance arc. At the initial moment, the low-frequency impedance arc radius is large, the slope is high, and the corrosion cycle increases. The low-frequency impedance arc radius gradually decreases and shrinks to the real part of the impedance, and the impedance spectrum gradually shifts to the left. When corrosive ions enter concrete, cementitious materials are consumed, and expansion products are produced. The dynamic elastic modulus evaluation parameters increase at the initial stage and decrease in the middle and later stages. The Wiener stochastic process model can well reflect the change of durability life of reinforced concrete in the corrosive environment. Steel and concrete life curve are presented three phase change characteristics, The first stage of steel bar life curve lasts longer, the second stage accelerates the degradation rate faster, and the life obtained by the random process of steel bar is less than that of concrete. The life of steel bar is more sensitive to chloride, while the life of concrete is more sensitive to sulfate.