Landfill　leachate　treatment　is　a　major　challenge　in　wastewater　treatment.　In　this　study,　two　sulfur-based　autotrophic-heterotrophic　denitrification　biofilters　(Ra　biofilter　with　room-temperature　molded　filler　and　Rb　biofilter　with　melt　molded　filler)　were　used　to　treat　kitchen-landfill　leachate　at　low　temperatures.　The　effects　of　reflux　ratio,　concentrations　of　NaHCO3,　and　Na2S2O3　on　the　total　nitrogen　removal　efficiency　were　analyzed,　and　based　on　response　surface　methodology,　the　optimum　parameters　were　determined.　After　optimization,　the　total　nitrogen　removal　efficiency　for　the　Ra　and　Rb　biofilters　increased　by　83%　and　81%,　respectively.　Moreover,　sulfur　based　autotrophic　denitrification　accounted　for　more　than　70%　of　the　nitrogen　removal　in　both　biofilters.　Based　on　high-throughput　sequencing　results,　the　functional　bacteria　exhibited　high　abundance　in　the　Ra　biofilter,　indicating　that　the　room-temperature　molded　filler　favored　the　enrichment　of　functional　bacteria.　These　findings　were　important　for　optimizing　the　operation　of　sulfur　autotrophic-heterotrophic　denitrification　biofilters　at　low　temperatures.