The　karst　tiankeng　is　a　special　and　grand　negative　terrain　on　the　surface,　that　maintains　a　unique　ecosystem.　However,　knowledge　about　bacterial　and　fungal　communities　in　karst　tiankengs　is　still　limited.　Therefore,　soil　samples　from　five　karst　tiankengs　were　collected　and　subjected　to　high-throughput　sequencing　of　16S　rRNA　and　ITS　genes,　and　multivariate　statistical　analysis.　The　results　showed　abundant　and　diversified　bacterial　and　fungal　communities　in　karst　tiankeng.　The　bacterial　communities　were　dominated　by　Proteobacteria　and　Acidobacteria,　and　the　fungal　communities　were　dominated　by　Ascomycota　and　Basidiomycota.　Statistical　analysis　revealed　significant　differences　in　bacterial　and　fungal　communities　among　the　five　karst　tiankengs,　which　may　indicate　that　the　distribution　of　bacterial　and　fungal　communities　was　driven　by　separate　karst　tiankengs.　The　co-occurrence　network　structure　was　characterized　by　highly　modularized　assembly　patterns　and　more　positive　interactions.　The　keystone　taxa　were　mainly　involved　in　nutrient　cycling　and　energy　metabolism.　The　null　model　analysis　results　showed　that　the　stochastic　process,　especially　dispersal　limitation,　tended　to　be　more　important　in　controlling　the　development　of　bacterial　and　fungal　communities　in　karst　tiankeng.　The　bacterial　community　structure　was　significantly　associated　with　soil　properties　(SWC,　TN,　AN,　and　BD),　while　the　fungal　community　structure　was　significantly　associated　with　soil　properties　(SWC　and　TP)　and　plant　diversity.　These　results　can　expand　our　knowledge　of　the　karst　tiankeng　microbiome.