This paper addresses evaluating the evolution of stress inside the casing-cement sheath-formation system during the cement-injecting,setting,completion and production stages.This full-life-cycle analysis of cement sheath integrity gives rise to as-sessment of potential failure mode(i.e.,tensile-mode,shear-mode,and micro-annu-lus)in different stages,and the prevention measures accordingly can be pro-posed.Considering the loading history,two regimes should be distinguished.Before the accomplishment of cementation,as the cement slurry can merely withstand its hydraulic pressure,the in-situ stress and the wellbore pressure are withstood by the rock and the casing,respectively.Once the cementation process is completed,the stress increment (e.g.,hydraulic fracturing pressure)is withstood by the casing-cement sheath-formation system.The autogenous shrinkage of cement adversely affects the resistance of the system to shear failure,tensile failure and micro-annulus,whereas a moderate swelling of cement is beneficial to the cement sheath integrity.In addition,the cement sheath integrity is strongly influenced by the depth: the failure is encountered more easily at shallow layer.Both the hydraulic fracturing pressure in the completion stage and the in-crease in casing temperature in the production stage may lead to tensile circumferential stress,and the hydraulic fracturing is the most critical stage for the integrity of cement sheath.