The　mechanical　properties　of　PBT-based　azide　propellants,　composed　of　a　3,3　＇-bis(azidomethyl)oxetane/tetrahydrofuran　(PBT)　copolymer　matrix　and　defective　ammonium　perchlorate　(AP)　crystals,　are　significantly　influenced　by　the　matrix-crystal　interface.　This　study　employed　molecular　dynamics　(MD)　simulations　to　examine　interfacial　effects　on　mechanical　performance　under　uniaxial　tensile　deformation.　Models　with　varying　cross-linking　densities　(70%,　80%,　90%)　and　AP　defect　widths　(20　&　Aring;,　30　&　Aring;,　40　&　Aring;)　were　analyzed　to　assess　the　effects　of　temperature,　strain　rate,　cross-linking　degree,　and　defect　size　on　interfacial　adhesion　strength　and　failure　mechanisms.　Results　indicate　that　at　low　temperatures,　the　interface　exhibited　high　stress　peaks　and　brittleness　characteristics,　transitioning　to　plastic　flow　and　enhanced　ductility　at　higher　temperatures.　Cross-linking　density　significantly　affects　interfacial　strength:　a　90%　cross-linking　degree　achieved　the　highest　stress　peak　and　optimal　tensile　resistance,　whereas　lower　cross-linking　resulted　in　weaker　stress　transfer　and　accelerated　post-peak　stress　decay.　Higher　strain　rates　increased　peak　stress　and　shortened　deformation　times,　while　lower　strain　rates　promoted　molecular　rearrangement,　enhancing　tensile　resistance.　Defect　size　also　plays　a　crucial　role,　with　smaller　defects　maintaining　interfacial　dominance,　whereas　larger　defects　shift　failure　toward　the　bulk　matrix,　reducing　stress　transfer　efficiency.　These　findings　provide　atomic-scale　insights　into　interfacial　defects　and　key　material　parameters,　offering　theoretical　guidance　for　optimizing　the　structural　stability　of　composite　propellants.