As　a　typical　viscoelastic　material,　solid　propellants　have　a　large　difference　in　mechanical　properties　under　static　and　dynamic　loading.　This　variability　is　manifested　in　the　difference　in　values　of　the　relaxation　modulus　and　dynamic　modulus,　which　serve　as　the　entry　point　for　studying　the　dynamic　and　static　mechanical　properties　of　propellants.　The　relaxation　modulus　and　dynamic　modulus　have　a　clear　integral　relationship　in　theory,　but　their　consistency　in　engineering　practice　has　never　been　verified.　In　this　paper,　by　introducing　the　＂catch-up　factor　lambda＂　and　＂waiting　factor　gamma＂,　a　method　for　the　inter-conversion　of　the　dynamic　storage　modulus　and　relaxation　modulus　of　HTPB　propellant　is　established,　and　the　consistency　between　them　is　verified.　The　results　show　that　the　time　region　of　the　calculated　conversion　values　of　the　relaxation　modulus　obtained　by　this　method　covers　10(-8)-10(4)　s,　spanning　twelve　orders　of　magnitude.　Compared　to　that　of　the　relaxation　modulus　(10(-4)-10(4)　s,　spanning　eight　orders　of　magnitude),　an　expansion　of　four　orders　of　magnitude　is　achieved.　This　enhances　the　expression　ability　of　the　relaxation　modulus　on　the　mechanical　properties　of　the　propellant.　Furthermore,　when　the　conversion　method　is　applied　to　the　dynamic-static　modulus　conversion　of　the　other　two　HTPB　propellants,　the　results　show　that　the　correlation　coefficient　between　the　calculated　and　measured　conversion　values　is　R-2　＞　0.933.　This　proves　the　applicability　of　this　method　to　the　dynamic-static　modulus　conversion　of　other　types　of　HTPB　propellants.　It　was　also　found　that　lambda　and　gamma　have　the　same　universal　optimal　value　for　different　HTPB　propellants.　As　a　bridge　for　static　and　dynamic　modulus　conversion,　this　method　greatly　expands　the　expression　ability　of　the　relaxation　modulus　and　dynamic　storage　modulus　on　the　mechanical　properties　of　the　HTPB　propellant,　which　is　of　great　significance　in　the　research　into　the　mechanical　properties　of　the　propellant.