Compared　with　high-voltage　transmission　cables,　10kV　distributed　cables　are　currently　receiving　less　attention.　Contrary　to　the　continuously　improving　national　overall　power　supply　reliability,　the　failure　rate　of　10kV　distribution　cables　is　not　optimistic.　Thermal　aging　is　an　important　cause　of　defects　in　distributed　cables,　which　further　develop　into　failures.　This　paper　conducts　research　on　defects　of　different　severity,　uses　FDR　to　determine　the　severity　of　defects,　and　analyzes　the　impact　of　defect　development　on　positioning　accuracy.　Firstly,　we　establish　a　simulation　model　of　the　aging　cable,　and　use　the　windowed　Fourier　transform　to　locate　the　multi-point　aging.　Then,　we　carry　out　relevant　experiments　based　on　the　simulation　results　to　further　verify　the　accuracy　of　the　algorithm.　The　simulation　and　test　results　show　that　for　cables　of　the　same　length,　the　aging　time　has　no　effect　on　the　defect　location　accuracy.　The　positioning　accuracy　of　simulation　and　test　algorithms　are　within　0.46%.　©　2021　IEEE.