As　a　classical　topological　circuit　model,　the　extended　Debye　model　is　of　great　significance　for　the　condition　diagnosis　of　oil　paper　insulation　equipment.　Aiming　at　the　uncertain　branches　and　the　random　identification　results　of　the　current　extended　Debye　model.　This　paper　based　on　the　branch　characteristics　of　the　model,　combining　the　real　and　imaginary　parts　relation　of　repolarization　rate　with　spectrum　differentiation　method,　proposing　a　spectrum　decomposition　method　to　realize　the　complete　identification　of　the　extended　Debye　model.　Undering　the　external　electric　field,　the　dielectric　relaxation　process　will　cover　the　conductivity　loss,　and　the　coupling　and　superposition　of　the　internal　multiple　polarization　maps　make　uncertainly　to　the　polarization　identification.　It　obscures　the　number　of　branches’s　determination　of　the　equivalent　model,　and　makes　the　identification　of　model　parameters　difficult.　In　order　to　solve　those　problems,　firstly,　the　frequency　domain　dielectric　spectrum　is　decoupled　based　on　Kramers-Kronig　transform.　Since　the　resistance　and　infinite　capacitance　terms　calculated　result　is　0,　the　real　and　imaginary　parts　of　the　complex　capacitance　calculated　by　K-K　relationship　only　contain　relaxation　polarization　components.　Therefore　it　can　realize　the　separation　of　the　geometric　branch　and　the　polarization　branch　of　the　extended　Debye　model,　and　can　also　complete　the　quantitative　extraction　of　the　insulation　resistance,　the　geometric　capacitance　and　the　relaxation　polarization　spectrum　line.　Then,　using　the　spectral　characteristics　of　resistance　and　capacitance,　the　unique　parameters　of　insulation　resistance　and　geometric　capacitance　can　be　determined　by　the　least　square　method.　Next,　according　to　the　spectrum　differentiation　method,　the　first-order　differentiation　of　the　real　part　of　the　polarization　complex　capacitance　is　carried　out.　Because　the　single　relaxation　polarization　real　part　is　a　ladder,　the　differential　spectrum　line　has　a　relaxation　peak　.　The　number　of　relaxation　mechanisms　can　be　confirmed　by　the　number　of　peak　points　of　differential　spectral　lines,　and　the　unique　polarization　equivalent　circuit　parameters　can　be　solved　by　using　the　uniqueness　of　peak　points.　Finally,　the　feasibility　of　this　method　is　verified　by　existing　model　parameters　and　examples:　the　identification　error　of　insulation　resistance　and　geometric　capacitance　parameters　is　less　than　1%,　the　polarization　equivalent　circuit　error　is　less　than　7%.　In　general,　the　calculated　and　measured　spectral　lines　are　in　good　agreement　and　the　trend　is　consistent.　The　spectral　deconstruction　method　can　provide　a　reliable　physical　model　for　the　study　of　the　internal　relaxation　characteristics　of　oil　paper　insulation.　Through　simulation　and　case　analysis,　the　following　conclusions　can　be　drawn:　①the　conductance　and　relaxation　processes　can　be　accurately　separated　by　K-K　transformation,　and　the　insulation　resistance　and　geometric　capacitance　parameters　can　be　determined.　②The　number　of　polarization　branches　of　the　extended　Debye　model　can　be　clearly　determined　by　the　peak　number　of　the　real　part　differential　spectral　line　of　the　polarization　complex　capacitance;　The　parameters　of　each　polarization　branch　can　be　identified　by　using　the　spectrum　differentiation　method　to　solve　the　spectrum　step　by　step.　③The　spectrum　deconstruction　method　proposed　in　this　paper　can　completely　identify　the　parameters　of　oil　paper　insulation　extended　Debye　model,　and　the　results　are　unique　within　a　certain　accuracy　range.　©　2023　Chinese　Machine　Press.　All　rights　reserved.