This　study　investigated　the　influence　of　C/N　ratios　and　tidal　strategies　on　nitrogen　removal　and　bacterial　communities　in　two　pilot-scale　tidal　flow　constructed　wetlands　(TFCWs)　with　simultaneous　nitrification-denitrification　process.　Heterotrophic　nitrification　aerobic　denitrification　(HNAD)　was　the　main　nitrogen　transformation　pathway　in　both　TFCWs.　High　C/N　ratios　and　effluent　circulation　at　low　temperature　promoted　HNAD　in　TFCWs　with　high　nitrogen　removal　efficiencies　(72.6%-95.5%　for　NH4+-N　and　70.9%similar　to　91.8%　for　TN).　Effluent　circulation　had　more　influence　on　bacterial　community　structure　and　diversity　than　C/N　ratios.　Among　16　detected　genera　related　to　nitrogen　removal,　HNAD　bacteria　(HNADB)　were　abundant.　Especially,　some　dominant　HNADB　(e.g.　Aeromonas,　Hydrogenophage　and　Gemmobacter)　were　core　genera,　showing　positive　interactions　with　other　genera　related　to　nitrogen　removal.　Tidal　strategies　had　more　contribution　to　the　shifts　in　these　genera　than　C/N　ratios.　This　study　highlights　the　importance　of　HNADB　in　pilot-scale　TFCWs　and　their　responses　to　C/N　ratios　and　tidal　strategies.