Removal　of　indoor　formaldehyde　is　important　but　challenging　due　to　the　very　low　concentration.　Here,　we　showed　the　applicability　of　a　new　class　of　conjugated　microporous　poly(aniline)s　(CMPAs)　in　this　formaldehyde　capture.　The　unique　properties　of　rich　ultramicroporosity　and　benzenoid　amine　(-NH-)　groups　made　the　resulting　CMPAs　ideal　platforms　for　the　efficient　low-concentration　formaldehyde　adsorption,　through　the　interaction　between　benzenoid　amine　groups　and　formaldehyde　via　Mannich　reaction　and　H-bond　in　the　ultramicropore.　They　therefore　exhibited　ultrafast　adsorption,　receiving　＞　80%　removal　efficiency　for　ca　0.7　ppm　formaldehyde　within　60　min,　and　benchmarking　storage　capacity,　achieving　ca.　2679.68　mg.g(-1)　for　CMPA-2.　Our　CMPAs　also　worked　well　in　a　self-assembled　air　clean　unit,　keeping　kinetically　reducing　average　98%　of　formaldehyde　after　treatment　of　4000　BV　polluted　air　(with　ca.　25　ppm　formaldehyde)　without　break-through.　Outcomes　highlighted　the　potential　of　CMPAs　for　the　clean-up　of　airborne　formaldehyde　for　human　health　protection　in　next　generation.　(C)　2021　Elsevier　Ltd.　All　rights　reserved.