Previous　studies　suggested　that　strong　positive　correlations　between　microbial　taxa　destabilized　the　microbial　communities,　because　high　synchrony　between　taxa　caused　different　taxa　responded　in　tandem　to　the　changes　of　environmental　conditions.　In　this　study,　we　used　nutrient　concentrations　(nitrogen　and　phosphorus)　as　indicators　for　anthropogenic　activities,　and　explored　the　effects　of　anthropogenic　activities　on　the　stability　of　bacterial　communities　in　a　subtropical　river,　Xiyuan　River.　We　also　used　co-occurrence　networks　to　indicate　the　synchrony　between　bacterial　taxa.　The　nutrient　concentrations　were　higher　in　the　midstream　and　downstream　areas　than　in　the　upstream　area　of　Xiyuan　River.　As　a　result,　the　average　proportion　and　correlation　coefficient　of　positive　correlations　were　higher　in　the　midstream　and　downstream　networks　than　in　the　upstream　networks.　This　indicates　that　frequent　anthropogenic　activities　increased　the　synchrony　between　taxa　in　the　midstream　and　downstream　communities,　and　therefore　destabilized　the　bacterial　communities.　To　further　explore　the　mechanisms,　we　found　that　the　changes　of　community　stabilities　associated　with　the　changes　of　bacterial　functions.　Anthropogenic　activity　tolerant　bacteria　(e.g.,　nutrient　removal,　aromatic　degradation　and　pathogen　bacteria)　and　their　linked　bacterial　taxa　formed　large　and　strong　positive　modules　in　the　midstream　and　downstream　networks,　and　thus　destabilized　the　communities.　Based　on　the　perspective　of　microbial　correlations,　our　results　provide　a　new　insight　in　the　mechanisms　of　how　anthropogenic　activities　alter　riverine　microbial　communities.