Landfill　leachate,　generated　from　the　wastes　in　a　landfill,　is　a　type　of　wastewater　with　high　concentrations　of　ammonia　and　organics,　causing　a　serious　environmental　pollution.　Because　of　its　complex　and　changing　characteristics,　it　is　difficult　to　remove　nitrogen　from　landfill　leachate　economically　and　effectively.　Hence,　nitrogen　removal　is　a　significant　research　priority　of　landfill　leachate　treatment　in　recent　years.　Biological　processes　are　known　to　be　effective　in　nitrogen　removal.　In　this　work,　the　biological　nitrogen　removal　treatments　were　divided　into　the　following　processes:　conventional　nitrification-denitrification　process,　nitritation-denitritation　process,　endogenous　denitritation　process,　and　anaerobic　ammonium　oxidation　(Anammox)　process.　This　manuscript　summarized　the　theories　and　applications　of　these　approaches　in　detail,　and　concluded　that　appropriate　processes　should　be　selected　in　accordance　with　different　characteristics　of　landfill　leachate,　in　order　to　effectively　remove　nitrogen　from　all　stages　of　landfill　leachate　and　reduce　disposal　costs.　Finally,　perspective　on　the　challenges　and　opportunities　of　biological　nitrogen　removal　from　landfill　leachate　was　also　presented.