Cholesterol　is　an　essential　compound　for　maintaining　cellular　homeostasis　and　human　healthy.　Sensitive　detection　of　cholesterol　and　efficient　elimination　of　excess　cholesterol　have　become　the　essential　manipulations　in　clinical　diagnosis　and　health　management.　To　date,　it　is　still　quite　challenging　that　cholesterol　detection　and　elimination　tasks　are　carried　out　simultaneously.　In　this　study,　bifunctional　magnetic　nanoparticles　(Fe3O4@PDA-PBA-CD)　are　designed　and　fabricated　to　overcome　this　difficulty.　Taking　advantages　of　competitive　host　guest　interaction　and　magnetic　separation,　highly　efficient,　reusable　and　simultaneous　cholesterol　detection　and　elimination　can　be　achieved.　The　limit　of　detection　is　determined　to　be　4.3　nM,　which　is　comparable　or　even　lower　than　existing　methods.　The　distinguished　performance　may　attribute　to　the　high　loading　efficiency　and　magnetic　enrichment　of　nanoparticles.　Besides,　this　efficient　strategy　is　resistant　to　interfering　substances,　thus　realizing　sensitive　cholesterol　detection　in　real　sample.　Simultaneously,　the　bifunctional　magnetic　nanoparticles　also　have　up　to　95%　cholesterol　elimination　efficiency,　which　is　higher　than　previous　reported　methods.　Furthermore,　the　nanoparticles　are　turned　out　to　be　reusable　within　5　times　without　noticeable　loss　in　cholesterol　elimination　efficiency.　Therefore,　the　bifunctional　magnetic　nanoparticles　fabricated　here　could　hold　great　potential　for　simultaneous　cholesterol　detection　and　elimination　in　practical　applications.