According　to　the　vibration　differential　equation　of　cantilever,　and　the　continuum　equation　of　fluid,　two　kinds　of　magnetic　fluid　dampers　mainly　used　in　spacecrafts　were　designed.　It　is　proved　that　different　shape　of　damper,　different　diameter　of　permanent　magnetic,　different　saturated　magnetization　intensity　of　magnetic　fluid　and　different　quantity　of　magnetic　fluid　have　influences　on　the　damping　performance　based　on　the　experiments　for　comparing　the　time　duration　for　vibration　vanishing.　It　is　also　concluded　that　the　diameter　of　permanent　magnetic,　saturated　magnetization　intensity　of　magnetic　fluid　and　quantity　of　magnetic　fluid　own　their　optimal　values　at　different　vibration　frequency.　The　results　provide　the　base　for　structural　optimization　of　magnetic　fluid　dampers　which　could　be　of　great　significance　for　the　design　of　spacecrafts　with　low　frequency　and　small　amplitude　vibration.　©　2017,　Editorial　Office　of　Journal　of　Vibration　and　Shock.　All　right　reserved.