To evaluate the lifetime performance of prestressed concrete bridges exposed to chloride penetration environment,a probabilistic and finite element-based lifetime performance assessment approach for prestressed concrete bridges is proposed.Firstly,three critical times in the degradation process are discussed and their computing formulas are presented.Secondly,an analysis program named CBDAS(Concrete Bridge Durability Analysis System) is written based on the numerical simulation methods with respect to the deterioration of materials’ mechanical properties,reduction of sectional areas and variation of overall structural mechanics performance.Finally,the assessment method for calculating time-variant system reliability of prestressed concrete bridges is proposed associated with the analysis program CBDAS,Monte-Carlo simulation and analysis technique of the system reliability.The lifetime performance of a prestressed concrete continuous bridge under chloride penetration-induced corrosion is investigated by using the time-variant system reliability.