The　assessment　of　corrosion　defects　to　determine　their　effect　on　pipeline　integrity　is　essential　for　pipe　managers　to　develop　a　scientific　maintenance　strategy.　In　this　work,　a　nonlinear　finite　element　(FE)　model　coupled　with　multi-physical　fields　was　developed　to　study　the　mechano-electrochemical　(M-E)　synergistic　effect　at　an　external　corrosion　defect　on　X100　pipeline　elbow.　The　results　indicated　that　bending　radius　has　an　apparent　effect　on　the　burst　pressure　of　the　corroded　pipe　elbow.　However,　anodic　and　cathodic　reactions　was　insensitive　to　bending　radius　under　normal　working　pressures.　Pipes　elbows　with　corrosion　defects　located　in　the　intrados　have　a　lower　burst　pressure　than　those　in　the　extrados　and　central　line　crowns.　When　the　deformation　or　stress　generated　at　the　corrosion　defect　was　elastic,　the　synergistic　mechano-electrochemical　interaction　effect　was　insignificant.　However,　when　the　depth　of　the　defect　or　the　applied　internal　pressure　of　the　elbow　was　sufficient　to　produce　a　local　plastic　strain　in　the　corroded　region,　the　corrosion　reaction　of　the　local　steel　at　the　defect　was　remarkably　enhanced.　Under　multiaxial　stress,　the　corrosive　behaviour　of　steel　in　the　defective　area　involved　numerous　local　galvanic　batteries,　with　the　anode　located　in　the　high-stress　zone　and　the　cathode　in　the　lower-stress　zone.　Anodic　polarisation　was　found　to　occur　in　high-stress　zone,　which　accelerated　local　corrosion.