First-stage　gas　turbine　blades　in　an　airplane　undergo　extreme　operating　conditions　under　high　temperature　and　high　stress　conditions,　usually　causing　nonhomogeneous　microstructural　degradation.　The　detailed　characterization　of　temperature-and　stress-induced　microstructural　degradation,　dislocation　and　elemental　variation　are　keys　for　failure　analysis.　In　our　study,　we　systematically　investigate　microstructural　degradation　on　an　ex　serviced　second-generation　superalloy-based　turbine　blade　from　an　aeroengine.　Defects　in　trailing　edges　are　mainly　sparse　dislocation　networks,　exhibit　a　low　stacking　fault　density,　and　are　in　an　initial　rafting　stage　in　most　regions.　The　most　severely　degraded　region　is　in　a　middle　stage　of　creep,　with　high　densities　of　network　dislocations　in　the　gamma　phase　and　stacking　faults　in　the　gamma＇　phase.　An　overall　reorganization　of　ex-service　turbine　blades　is　built,　and　the　relationship　between　service　and　microstructural　degradation　is　revealed.　With　this　study,　we　provide　guidance　on　microstructural　degradation　evaluation　and　failure　analysis　in　conventional　single-crystal　turbine　blades.