The　quantitative　evaluation　of　the　cable　life　has　always　been　a　technical　problem.　An　equivalent　thermal　circuit　model　of　multi-loop　trench　laying　cables　is　proposed　for　the　fast　calculation　of　the　conductor　temperature　rise.　The　thermal　coupling　between　multiple　loops　of　the　cables　is　characterized　by　the　mutual　thermal　resistance.　The　relationship　between　the　current　of　cable　and　the　conductor　temperature　rise　is　derived.　A　numerical　model　used　to　calculate　the　conductor　temperature　rise　under　real-time　current　is　put　forward　based　on　thermal　circuit　model.　Then,　Arrhenius　equation　is　used　to　calculate　the　thermal　aging　life　of　the　insulation　material　under　different　currents.　By　comparing　the　result　of　the　proposed　thermal　circuit　model　with　that　of　the　FEM　and　IEC　standard,　the　correctness　of　the　thermal　circuit　model　has　been　verified.　It　is　shown　from　the　results　that　the　thermal　aging　life　of　the　XLPE　cable　decreases　obviously　at　high　conductor　temperature　with　the　increasing　current.　The　more　cable　loops　and　larger　current　applied　in　adjacent　cables　will　also　cause　a　decrease　of　the　cable　life.　©　2019　IEEE.