Most　of　the　engineering　vibrations　are　harmful,　due　to　many　unfavorable　consequences　caused　by　them,　such　as　structural　damage,　poor　working　accuracy,　etc.,　making　it　necessary　to　implement　vibration　isolation　measures.　Traditional　linear　vibration　isolation　methods　have　significant　deficiencies　regarding　isolating　low-frequency　vibrations,　in　which　the　stiffness　of　the　isolation　system　becomes　a　dominant　factor.　The　quasi-zero-stiffness　(QZS)　vibration　isolation　technology,　developed　in　recent　decades,　can　greatly　reduce　the　dynamic　stiffness　without　reducing　the　static　stiffness　and　thus　extend　the　vibration　isolation　frequency　band　to　low　frequency　region.　A　variety　of　approaches　for　constructing　QZS　isolators　have　been　proposed　based　on　geometric　nonlinearity,　magnetic　nonlinearity,　deformable　components　and　so　on.　With　higher　demands　and　more　complex　operating　conditions,　many　improvement　strategies　have　been　proposed　to　further　enhance　the　overall　performance　of　QZS　isolators　from　various　aspects.　To　date,　a　small　portion　of　theoretical　achievements　in　QZS　vibration　isolation　have　been　applied　in　engineering　fields,　showing　great　advantages　over　linear　vibration　isolation　methods.　In　these　contexts,　a　comprehensive　review　of　the　QZS　vibration　isolation　technology　is　essential.　This　paper　is　devoted　to　summarize　the　main　research　progress　of　QZS　vibration　isolation　in　terms　of　designs,　improvement　strategies　and　applications,　to　provide　a　general　overview　of　the　QZS　vibration　isolation　technology　for　researchers　in　related　fields.