Covalent　organic　framework　(COF)　film-based　solid-phase　extraction　(F-SPE)　has　garnered　great　attention　in　sample　pretreatment.　However,　harsh　synthesis　conditions　of　COF　films　have　severely　hindered　their　potential　applications.　In　this　study,　a　kind　of　COF　(TPB-DMTP)　films　were　fabricated　via　a　liquid-liquid　interfacial　synthesis　method　at　a　mild　condition.　The　obtained　films　exhibited　excellent　extraction　performance　towards　microcystins　(MCs,　an　algal　toxin)　due　to　their　porous　structure,　high　specific　surface　area　and　abundant　accessible　adsorption　sites.　Coupled　TPB-DMTP　films-based　F-SPE　with　high-performance　liquid　chromatography-tandem　mass　spectrometry　(HPLC-MS/MS),　a　sensitive　and　environment-friendly　analytical　method　was　established　for　MCs　detection.　Under　the　optimal　conditions,　this　method　possessed　wide　linear　ranges　(2.0-800.0　pg　mL-1)　with　good　linearity　(R　＞=　0.9991),　low　limits　of　detection　(0.8-3.0　pg　mL-1)　and　satisfactory　precision　(RSDs　＜=　7.1　%),　which　then　successfully　applied　for　MCs　detection　in　actual　aquatic　organism　samples.　Trace　amounts　of　MC-RR　(42.4　pg　mL-1)　and　MC-YR　(14.6　pg　mL-1)　were　detected　in　the　mussels.　The　results　demonstrate　the　excellent　application　potential　of　COF　films　in　sample　pretreatment.