A　3D　microscopic　numerical　model　for　chloride　diffusion　in　fatigue-damaged　concrete　was　established,　where　the　concrete　was　treated　as　a　three-phase　composite　consisting　of　coarse　aggregate,　mortar　matrix　and　ITZ　to　consider　its　inhomogeneity.　Results　showed　that　the　chloride　concentration　in　concrete　increases　significantly　with　the　increase　of　fatigue　stress　level,　water-cement　ratio,　temperature　and　exposure　time,　in　which　the　chloride　concentration　at　the　same　depth　is　different.　According　to　the　K-S　test,　the　chloride　concentration　at　a　certain　concrete　depth　follows　the　mixed　normal　distribution　at　a　5%　significance　level,　based　on　which,　a　probabilistic　fatigue　life　prediction　model　is　proposed.　It　was　found　that　the　failure　probability　increases　with　the　increase　of　fatigue　life,　but　decreases　with　the　decrease　of　fatigue　stress　level,　water-cement　ratio,　temperature　and　exposure　time.　Hence　it　was　suggested　that　RC　structure　should　be　maintained　a　fatigue　stress　level　of　below　0.　4　(failure　probability　of　10%　and　2　million　cycles　of　fatigue　life)during　its　service　.　In　addition,　based　on　the　proposed　model,　the　fatigue　life　of　RC　structures　in　four　coastal　cities　was　predicted　and　the　related　durability　recommendations　were　given.　©　2024　Cailiao　Daobaoshe/　Materials　Review.　All　rights　reserved.