Sample　preparation　is　crucial　in　analytical　chemistry,　impacting　result　accuracy,　sensitivity,　and　reliability.　Solid-phase　separation　media,　especially　adsorbents,　are　vital　for　preparing　of　liquid　and　gas　samples,　commonly　analyzed　by　most　analytical　instruments.　With　the　advancements　in　materials　science,　covalent　organic　frameworks　(COFs)　constructed　through　strong　covalent　bonds,　have　been　increasingly　employed　in　sample　preparation　in　recent　years.　COFs　have　outstanding　selectivity　and/or　excellent　adsorption　capacity　for　a　single　target　or　can　selectively　adsorb　multiple　targets　from　complex　matrix,　due　to　their　large　specific　surface　area,　adjustable　pore　size,　easy　modification,　and　stable　chemical　properties.　In　this　review,　we　summarize　the　classification　of　COFs,　such　as　pristine　COFs,　COF　composite　particles,　and　COFs-based　substrates.　We　aim　to　provide　a　comprehensive　understanding　of　the　different　classifications　of　COFs　in　sample　preparation　within　the　last　three　years.　The　challenges　and　development　trends　of　COFs　in　sample　preparation　are　also　presented.