According to the corrosion ions in the groundwater and soil of the platforms along Lanzhou metro，four kinds of compound salt solutions containing SO2-4，Cl-，and Mg2+ were prepared. The reinforced concrete specimens were placed in the compound salt solution，and nondestructive testing was conducted every 90 days by an electrochemical workstation and ultrasonic sound velocity detector. A durability life prediction model of reinforced concrete was established by using a non-monotone Wiener stochastic degradation process. When the relative dynamic modulus of elasticity reached 0.4，it was regarded as the failure condition of concrete，and when the crack width reached 0.2 mm，the corrosion current density was used as the failure threshold of reinforcement in concrete. 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 the concrete，cementitious materials are consumed，and expansion products are produced. When the crack width reaches 0.2 mm，the failure threshold of the corrosion current density is 7.637 5 μA/cm2. The life of steel bars is less than that of concrete through Wiener random process. The life of steel bars is about 7 200 days，2 900 days，4 500 days，and 2 000 days，respectively，in A，B，C，and D solutions，while the life of concrete in the solutions is about 10 000 days，6 500 days，5 500 days，and 5 000 days，respectively. Moreover，the life of steel bars is more sensitive to chloride，while the life of concrete is more sensitive to sulfate.