Abstract: The durability experiment of prestressed concrete specimens in the bending tensile status or in the directly compressive status in carbonation environment has been carried out. The degradation mechanism of prestressed concrete structure under the coaction of stress and carbonation corrosion is discussed. Assuming the index of carbonation time in Theory of Steady Diffusion is constant( i. e. A = 0.50) or variable, the mult-i factor model predicting the carbonation depth of prestressed concrete structure has been constructed, with introducing the stress status function which describes the relationship between carbonation depth and stress status. In addition, the prediction model of carbonation depth is analyzed with the first order reliability method ( FORM ) . The results indicate that the tensile or compressive stress are able to accelerate or slow down the concrete carbonation, respectively, and reflects the effects of the stresses very well, and the optimum index of carbonation time = 0.48 . If let = 0.50, the calculation results are also adequately accurate, which coincide with Theory of Steady Diffusion. Moreover, the deviation degree of carbonation depth of prestressed concrete structures, which is calculated with FORM, is very reliable.