Development　of　a　simple,　highly　selective,　and　sensitive　analytical　method　for　phthalate　monoesters　(mPAEs)　remains　a　challenge　due　to　the　complexity　of　biological　samples.　To　address　this　issue,　Cu2+　immobilized　magnetic　covalent　organic　frameworks　(Fe3O4@TtDt@Cu2+　composites)　with　core-shell　structures　were　pre-pared　to　enhance　the　enrichment　efficiency　of　mPAEs　by　a　facile　approach　synthesis　of　COFs　shells　with　inherent　bifunctional　groups　on　Fe3O4　NPs　and　further　Cu2+　immobilization.　The　composites　exhibit　high　specific　surface　area　(348.1　m(2)　g(-1)),　outstanding　saturation　magnetization　(34.94　emu　g(-1)),　ordered　mesoporous　structure,　Cu2+　immobilization,　and　excellent　thermal　stability.　Accordingly,　a　magnetic　solid-phase　extraction　(MSPE)　pre-treatment　technique　based　on　Cu2+　immobilized　COF　composites　combined　with　high-performance　liquid　chromatography-tandem　mass　spectrometry　(HPLC-MS/MS)　was　established,　and　key　parameters　including　the　adsorbent　amount,　adsorption　time,　elution　solvent,　etc.　were　examined　in　detail.　The　developed　analytical　method　showed　wide　linear　ranges　(10-8000　ng　L-1),　low　limit　of　detections　(LODs,　2-10　ng　L-1),　and　good　correlation　coefficients　(R-2　＞=　0.9904)　for　the　five　mPAEs.　Furthermore,　the　analytical　method　was　also　suc-cessfully　applied　to　the　highly　sensitive　detection　of　metabolite　mPAEs　in　mouse　plasma　samples,　indicating　the　promising　application　of　the　Fe3O4@TtDt@Cu2+　composites　as　a　quick　and　efficient　adsorbent　in　the　sample　pretreatment.