Despite　great　achievement　that　has　been　made　in　the　synthesis　of　covalent　organic　frameworks　(COFs),　precise　construction　of　COFs　with　well-defined　nano/microstructures　poses　a　rigorous　challenge.　Herein,　we　introduce　a　simple　template-free　strategy　for　controllable　synthesis　of　hollow　microtubular　COFs.　The　obtained　COFs　show　a　spontaneous　morphology　transformation　from　a　microfiber　to　a　hollow　microtubular　structure　when　the　concentrations　of　catalytic　acid　are　regulated　elaborately.　Furthermore,　the　as-prepared　COFs　exhibit　high　crystallinity,　well-defined　hollow　tubular　morphology,　and　high　surface　areas　(similar　to　2600　m(2)/g).　Taking　the　advantages　of　the　unique　morphological　structure,　the　hollow　microtubular　COFs　can　serve　as　an　ideal　host　material　for　enzymes.　The　resultant　biocomposites　show　high　catalytic　performance　and　can　be　successfully　applied　to　rapid　and　high-efficiency　proteolysis　of　proteins.　This　work　blazes　a　trail　for　controllable　synthesis　of　the　hollow　microtubular　COFs　through　a　template-free　process　and　expands　the　application　of　COFs　as　a　promising　platform　for　enzyme　immobilization.