Metallized　polypropylene　film　capacitors　are　subjected　to　high　pulse　voltage,　high　temperature,　and　mechanical　stress　for　a　long　time,　which　causes　material　degradation　and　seriously　threatens　the　operational　reliability　of　the　entire　system.　The　relevant　research　on　polypropylene　materials　for　film　capacitors　is　summarized　in　order　to　clarify　the　degradation　mechanism　of　film　capacitors,　grasp　the　key　parameters　affecting　the　degradation　of　film　capacitors,　and　sort　out　the　reliability　and　applicability　of　existing　state　detection　and　lifetime　prediction　methods.　Firstly,　under　the　influence　of　multiple　physical　fields,　the　degradation　of　polypropylene　film　materials　is　closely　related　to　space　charge　transport,　partial　discharge　phenomenon,　self-healing,　and　breakdown　behavior.　The　intrinsic　parameters　of　the　material　(such　as　crystallinity,　film　thickness,　square　resistance　of　the　metallized　film)　and　external　factors　(such　as　voltage　form,　pulse　frequency,　external　temperature)　can　affect　the　above　parameters　or　processes.　The　injection　and　detrapping　of　space　charges　are　the　main　factors　leading　to　material　degradation.　However,　traditional　space　charge　measurement　methods　currently　cannot　meet　the　space　charge　measurement　needs　of　μm　level　film　materials,　and　there　is　an　urgent　need　to　develop　high-resolution　space　charge　measurement　methods.　Secondly,　electrical　stress,　thermal　stress,　mechanical　stress,　and　their　coupling　effects　can　affect　the　aging　process　of　polypropylene　materials.　These　factors　first　cause　changes　in　the　material　structure,　such　as　recrystallization,　molecular　chain　breakage,　altering　the　trap　characteristics　and　carrier　transport　behavior　of　the　material.　This　is　then　reflected　in　the　macroscopic　performance　changes.　Therefore,　aging　tests　are　very　important　in　the　material　development　process.　However,　the　aging　of　film　capacitor　materials　under　the　coupling　of　multiple　physical　fields　is　difficult　to　reproduce　in　the　laboratory,　which　means　that　most　current　research　on　the　aging　of　polypropylene　materials　only　considers　a　single　factor.　It　is　urgent　to　conduct　aging　experiments　under　the　coupling　of　multiple　physical　fields　that　are　close　to　actual　working　conditions,　in　order　to　clarify　the　aging　mechanism　of　film　capacitor　materials.　Furthermore,　further　research　is　needed　on　how　to　decouple　multiple　stress　aging.　Finally,　effective　diagnostic　and　lifetime　prediction　methods　can　improve　the　reliability　of　the　system.　The　aging　diagnosis　methods　for　film　capacitors　include　partial　discharge　diagnosis　method,　polarization　and　depolarization　current　method,　tanδ　detection　method,　and　capacitance　detection　method.　The　DC　partial　discharge　detection　method　can　be　used　to　determine　the　type　of　defect　and　provide　guidance　for　the　production　process　of　materials.　However,　this　part　of　the　research　is　still　in　its　infancy　in　China.　Other　diagnostic　methods　have　various　shortcomings　and　deficiencies.　It　is　necessary　to　develop　aging　diagnosis　methods　that　combine　multiple　criteria　and　means.　The　methods　for　lifetime　prediction　of　film　capacitors　include　traditional　probability　statistical　method,　probability　statistical　method　considering　performance　degradation,　and　prediction　method　based　on　machine　learning.　These　lifetime　prediction　models　cannot　fully　consider　failure　mechanism,　resulting　in　low　prediction　accuracy　and　limited　applications.　In　the　future,　the　lifetime　prediction　technology　of　film　capacitors　can　be　further　developed　by　in-depth　studying　the　aging　mechanism　and　combining　intelligent　recognition　and　machine　algorithm.　©　2025　China　Machine　Press.　All　rights　reserved.