Particle　dampers　have　good　performance　of　vibration　control　and　noise　reduction,　and　they　have　been　widely　studied　and　applied　in　the　field　of　high-frequency　vibration　control,　such　as　aviation　and　mechanical　engineering.　However,　the　vibration　characteristics　of　civil　engineering　structures　are　usually　low　frequency　and　low　amplitude,　which　restricts　the　performance　of　particle　dampers.　A　new　type　of　particle　damper,　namely　the　multiple　unidirectional　single-particle　damper　(MUSPD),　is　advanced　based　on　the　comparative　analysis　of　the　construction　characteristics,　damping　performance,　and　damping　mechanism　of　a　single-particle　damper　and　multiparticle　damper.　Based　on　the　analysis　of　the　damping　mechanism　of　MUSPD　and　the　integral　consideration　of　the　stress　state　of　particles,　the　mechanical　model　of　MUSPD　is　established,　and　an　efficient　numerical　calculation　method　with　variable　step　size　is　proposed.　For　harmonic　excitation,　the　relationship　between　the　optimal　motion　distance　of　a　particle　and　other　parameters　is　established　by　theoretical　analysis.　In　addition,　the　optimization　analysis　method　of　MUSPD　subjected　to　ground　motions　is　proposed,　and　the　rationality　and　accuracy　are　all　verified.　The　results　show　that　MUSPD　has　a　better　damping　effect　than　a　classical　particle　damper.　Because　the　MUSPD　belongs　to　acceleration　(force)-related　dampers,　the　energy　of　the　controlled　structure　will　be　transferred　as　long　as　the　particles　collide　with　the　controlled　structure,　and　the　frequency　richness　and　randomness　of　the　ground　motion　spectrum　enhance　the　probability　of　particles　colliding　with　the　controlled　structure.　Moreover,　the　site　effect　has　no　obvious　influence　on　the　damping　effect　of　MUSPD,　and　it　is　more　suitable　for　middle-　and　low-rise　structures.