Return　voltage　measurement　(RVM)　is　an　effective　dielectric　response　test　method　and　has　been　used　to　evaluate　aging　status　of　solid　insulation.　In　the　process　of　field　test,　the　polarization　spectrum　obtained　is　non-standard　which　is　affected　by　many　factors,　and　the　insulation　status　of　dielectric　is　hard　to　judge.　Factors　that　affect　field　test　return　voltage　polarization　spectrum　were　analyzed,　method　of　judging　and　explaining　the　non-standard　polarization　spectrum　was　provided.　Reliability　and　preciseness　of　judging　solid　insulation　status　with　polarization　spectrum　were　improved.　This　method　have　great　reference　value　in　engineering　practice.