The　quasi-zero　stiffness　(QZS)　system,　as　a　typical　high-static-low-dynamic-stiffness　(HSLDS)　system,　is　able　to　realize　low　frequency　vibration　isolation　by　introducing　nonlinear　negative　stiffness.　However,　the　nonlinearity　of　the　system　may　result　in　a　serious　deterioration　of　the　isolation　performance　under　large　amplitude　excitation.　In　this　paper,　an　inerter-based　combined　vibration　isolation　(IBCVI)　system　is　proposed　to　overcome　this　problem.　The　IBCVI　system　consists　of　a　QZS　system　and　an　inerter-based　linear　dynamic　vibration　absorber　(IBDVA).　The　harmonic　balance　method　is　employed　to　obtain　amplitude-frequency　response　of　the　IBCVI　system,　and　the　mechanism　of　IBDVA　on　vibration　isolation　system　is　revealed.　Then　the　effects　of　system　parameters　on　control　performance　are　studied　in　detail.　The　results　of　the　comparison　with　other　models　show　that　the　presented　model　performs　smaller　vibration　amplitude　and　wider　isolation　frequency　band.　This　research　provides　a　new　insight　into　vibration　isolation　under　large　amplitude　excitation　from　the　perspective　of　vibration　absorption.