In　this　paper,　an　enhanced　prismatic-element　scaled　boundary　perfectly　matched　layer　(SBPML)　is　developed,　which　is　a　novel　time-domain　artificial　boundary　method　for　3D　infinite　wave　problems.　The　SBPML　permits　the　utilization　of　an　artificial　boundary　with　general　geometry　and　can　consider　planar　physical　surfaces　and　interfaces　extending　to　infinity.　Moreover,　this　enhancement　enables　the　seamless　integration　with　surface　meshes　of　arbitrary　polygonal　faces　(such　as　triangles,　quadrangles,　pentagons,　heptagons,　octagons,　etc.)　at　the　truncation　boundaries.　The　interior　domain　can　be　modelled　by　polyhedrons　formulated　by　the　scaled　boundary　finite　element　method　(SBFEM).　The　geometric　shape　of　the　SBPML　elements　in　the　proposed　method,　within　the　local　coordinate　system,　takes　the　form　of　a　regular　prism　with　regular　polygonal　top　and　bottom　faces.　Consequently,　it　is　referred　to　as　the　Prismatic-element　SBPML.　Local　scaled　boundary　coordinates　based　on　the　polygonal　shape　function　are　firstly　introduced　into　the　truncated　infinite　domain　to　describe　its　general　geometry　properties　and　provide　the　coupled　capabilities　with　arbitrary　polygonal　face　meshes　at　the　truncation　boundaries　of　numerical　models.　Then,　a　complex　stretching　function　from　PML　is　applied　to　radial　direction　of　the　local　scaled　boundary　coordinates　to　map　the　physical　space　onto　the　complex　space,　resulting　in　a　SBPML　domain.　Upon　spatial　discretization,　the　proposed　method　is　formulated　using　a　2nd-order　mixed　displacement-stress　unsplit-field　formulation,　allowing　seamless　coupling　with　FEM　and　SBFEM　originally　designed　for　the　interior　computational　domain.　Finally,　three　benchmark　examples　of　wave　propagation　problems　in　unbounded　domains　and　two　soil-structure　interaction　problems　of　engineering　problems　are　presented　to　demonstrate　the　accuracy　and　robustness　of　the　Prismatic-element　SBPML.　©　2024