Background　Karst　tiankeng　is　a　large-scale　negative　surface　terrain,　and　slope　aspects　affect　the　soil　conditions,　vegetation　and　microbial　flora　in　the　tiankeng.　However,　the　influence　of　the　slope　aspect　on　the　soil　microbial　community　in　tiankeng　has　not　been　elucidated.　Methods　In　this　study,　metagenomic　sequencing　technology　was　used　to　analyze　the　soil　microbial　community　structure　and　functional　potentials　on　the　shady　and　sunny　slopes　of　karst　tiankeng.　Results　The　Shannon-Wiener　diversity　of　microbial　communities　on　shady　slope　(SHS)　was　significantly　higher　than　that　on　sunny　slope　(SUS).　Although　the　composition　of　dominant　phyla　on　shady　slope　(SHS)　and　sunny　slope　(SUS)　was　similar,　there　were　significant　differences　in　beta-diversity.　The　linear　discriminate　analysis　(LDA)　results　showed　that　biomarkers　mainly　belongs　to　Actinobacteria,　Chloroflexi　and　Proteobacteria.　Functional　pathways　and　CAZy　(Carbohydrate-Active　Enzymes)　genes　also　had　a　remarkable　response　to　slope　aspect　change.　LEfSe　results　indicated　several　biomarker　pathways　in　sunny　slope　involved　in　human　disease.　Moreover,　the　abundance　of　CAZy　genes　was　higher　in　shady　slope　and　had　stronger　ability　in　decomposing　litter.　The　microbial　communities　were　mainly　correlation　with　the　vegetation　characteristics　(species　richness　and　coverage)　and　soil　properties　(SOC　and　pH).　Conclusions　These　results　indicate　slope　aspect　has　a　pronounced　influence　on　microbial　community　composition,　structure　and　function　at　karst　tiankeng.　In　the　future,　the　conservation　of　karst　tiankeng　biodiversity　should　pay　more　attention　to　topographical　factors.