Chromium　(VI)　is　a　ubiquitous　groundwater　contaminant　and　it　is　dangerous　to　both　ecological　and　human　health.　Iron　nanoparticles　(nFe)　have　a　large　specific　surface　area　and　they　are　highly　efficient　in　removing　chromium　(VI)　from　aqueous　solution.　However,　since　the　traditional　reductive　synthesis　of　nFe　is　relatively　expensive　and　often　causes　secondary　pollution,　it　is　necessary　to　develop　a　low-cost　green　synthetic　method　using　plant　extracts.　Synthetic　conditions　are　important　for　obtaining　highly　active　chromium-removing　nanomaterials.　In　this　paper,　a　green　tea　extract　was　used　to　prepare　nFe　and　the　effects　of　synthetic　conditions　on　subsequent　remediation　performance　were　investigated.　The　optimal　conditions　included　a　green　tea　extract/Fe2+　ratio　of　1:2　(91.6%),　a　green　tea　extract　temperature　of　353　K　(88.3%)　and　a　synthetic　temperature　of　298　K　(88.1%).　Advanced　material　characterization　techniques,　including　XPS,　SEM-EDS,　TEM,　and　Brunauer-Emmett-Teller　(BET)　confirmed　that　the　average　particle　size　was　between　50-80　nm,　with　a　specific　surface　area　of　42.25　m2·g-1.　Furthermore　nFe　had　a　core-shell　structure,　where　Fe　(0)　constituted　the　core　and　a　shell　was　composed　of　iron　oxide.　Finally,　a　mechanism　for　synthesizing　nFe　by　green　tea　extract　was　proposed,　providing　a　theoretical　basis　for　optimized　synthetic　conditions　for　preparing　nFe　when　using　green　tea　extract.