The　thermally　expandable　microspheres　(TEMs)　were　prepared　via　suspension　polymerization　with　acrylonitrile　(AN),　methyl　methacrylate　(MMA)　and　methyl　acrylate　(MA)　as　monomers　and　n-hexane　as　the　blowing　agent.　Meanwhile,　a　novel　type　of　functional　and　conductive　thermal　expandable　microsphere　was　obtained　through　strongly　covering　the　surface　of　microsphere　by　conductive　polymers　with　the　mass　loading　of　1.5%.　The　optimal　conditions　to　prepare　high　foaming　ratio　and　equally　distributed　microcapsules　were　investigated　with　AN-MMA-MA　in　the　proportion　of　70%/20%/10%　(m/m/　m),　and　25　wt%　of　n-hexane　in　oil　phase.　The　further　investigation　results　showed　that　the　unexpanded　TEMs　were　about　30　mm　in　diameter　and　the　maximum　expansion　ratio　was　nearly　125　times　of　original　volume.　The　polypyrrole　(PPy)　was　smoothly　coated　on　the　surface　of　the　TEMs　and　the　expansion　property　of　PPy-coated　TEMs　was　almost　the　same　as　the　uncoated　TEMs.　Moreover,　the　structure　and　expanding　performance　of　TEMs　and　PPy-coated　TEMs　were　characterized　by　scanning　electron　microscopy　(SEM),　laser　particle　size　analyzer　and　dilatometer　(DIL).　(C)　2016　Chinese　Chemical　Society　and　Institute　of　Materia　Medica,　Chinese　Academy　of　Medical　Sciences.　Published　by　Elsevier　B.V.　All　rights　reserved.