The　negative　topographic　slopes　in　a　degraded　karst　tiankeng　play　an　important　role　in　protecting　plant　diversity.　Studying　the　functional　diversity　of　soil　microbial　communities　on　slopes　AIDS　in　clarifying　the　ecological　characteristics　and　spalial　distribution　of　soil,　to　explore　the　relationship　between　soil　microorganisms　and　plant　diversity,　and　to　assess　the　biodiversity　of　degraded　karsl　tiankengs.　The　degraded　tiankeng　＂　Bajiaxiantang＂　of　Zhanyi　county　in　Yunnan　Province　was　selected　as　the　study　site,　A　Biolog　MicroPlate　was　used　to　analyze　the　functional　diversity　of　the　soil　microbial　community　in　the　sloj＞e　environment　and　how　soil　microbial　community　functional　diversity　varied　with　gradient　(pit,　uphill,　mid-slope,　downhill,　and　pit　bottom).　The　results　showed　that　the　functional　diversity　indices　(Shannon,　Simpson,　and　Mcintosh)　and　the　carbon　source　utilization　degree　of　the　soil　microbial　communities　at　the　pit　bottom　were　slightly　higher　than　those　at　the　pit　level　and　were　significantly　higher　than　those　at　the　mid-slope　level,　showing　a　trend　of　downhill＞mid-slope＞uphill.　The　main　sources　of　carbon　used　by　soil　microbial　community　on　slope　are　sugars　and　amino　acids..　The　two　principal　components　account　for　31.9%　and　28.7%　of　all　variance　and　can　distinguish　the　carbon　source　utilization　of　soil　microbial　communities　in　different　slope　positions.　The　a　diversity　index　of　herbaceous　plants　inside　and　outside　the　pit　was　significantly　different.　The　diversity　index　of　woody　plants　on　the　slope　was　significantly　different　(P＜0.05),　and　the　diversity　index　of　the　woody　plants　was　highest　downhill.　The　p　diversity　index　showed　that　the　habitats　of　the　different　slopes　are　different　and　that　the　habitats　of　the　downhill　area　are　the　most　diverse.　The　study　found　that　the　unique　negative　topography　and　soil　environment　of　the　degraded　karst　tiankeng　talus　slopes　led　to　to　higher　plant　diversity　and　higher　functional　diversity　of　soil　microbial　communities,　and　that　the　spatial　distribution　of　the　two　is　consistent.　Thus,　special　attention　should　l＞e　paid　to　the　value　of　underground　forest　resources　on　the　talus　slopes.　©　2019　Science　Press.　All　rights　reserved.