Tunnel and underground engineering projects have certain failure risks during construction and operation, including the risk of durability failure to which the study is not enough. In this paper, a whole set of research method for analysis, assessment and calculation on durability risk was proposed on the basis of identification to durability risk factors of large underground concrete structures. That is: this paper provided a method of reliability calculation by establishing failure mode and limit-state-equations according to reliability theory; then, classified and collated various risk factors by taking methods of analytic hierarchy process (AHP) and fault tree analysis (FTA); after that, the quantitative analysis of structural durability was done in accordance with Monte - Carlo (M-C) method. Finally, as an example, for the project of passage across the Yangtze River in Chongming, Shanghai, the above methods were applied to estimate the risk of durability failure of segment component. Effective measures and methods were presented and adopted to enhance the durability capacity of structure according to the results of analysis and assessment.