In　this　paper,　we　introduce　a　novel　direct　time-domain　artificial　boundary　condition,　called　the　scaled　boundary　perfectly　matched　layer,　for　wave　problems　in　3D　unbounded　fluid-saturated　poroelastic　medium.　The　poroelastic　medium　is　conceptualized　as　a　two-phase　medium　composed　of　a　solid　skeleton　and　an　interstitial　fluid　based　on　the　u　-p　formulation　of　Biot＇s　theory.　The　scaled　boundary　perfectly　matched　layer　proposed　in　this　work　originates　from　an　extension　of　a　recently　developed　perfectly　matched　layer　for　wave　problems　in　a　single-phase　solid　medium.　The　dependence　of　the　conventional　perfectly　matched　layer　on　the　global　coordinate　system　is　overcome　in　the　present　method.　As　a　result,　this　method　permits　the　utilization　of　an　artificial　boundary　with　general　geometry　(not　necessarily　convex)　and　can　consider　planar　physical　surfaces　and　interfaces　extending　to　infinity.　The　proposed　method　is　formulated　by　a　mixed　unsplit-field　form,　which　includes　both　the　mixed　displacement-stress　field　and　pore　pressure-relative　displacement　field.　The　resulting　scaled　boundary　perfectly　matched　layer　formulation　can　be　directly　described　by　a　system　of　third-order　ordinary　differential　equations　in　time,　which　can　be　easily　integrated　into　the　standard　finite-element　framework　of　poroelastic　theory.　Finally,　numerical　benchmark　examples　are　presented　to　demonstrate　the　accuracy　and　robustness　of　the　proposed　scaled　boundary　perfectly　matched　layer,　as　well　as　the　versatility　in　practical　engineering　problems.