In this study, a durability design theory system for engineering structures' whole life-cycle design is established. The new theory system is based on the relationships between performances, cost and service life of structures in the whole life time domain. The performance index, economic index and service life index are considered as key indexes in the whole system. Based on the established system, the limit state for durability design could be determined and the features of durability limit state are also analyzed. The proposed new durability design theory system could be used in structural performance optimization in whole life period and consequently results in the promotion of environment-friendly and resource conservation.