Chlorophyll-a　(Chla)　can　intuitively　reflect　the　degree　of　cutrophication　of　water,　Chla　concentration　can　be　accurately　estimated　via　the　three-band　bio-optical　model　because　it　can　weaken　the　influence　of　factors　such　as　suspended　and　yellow　matter　in　casc-11　waters.　Therefore,　the　approximate　position　of　the　three-band　factor　was　determined　by　analyzing　the　spectral　characteristics　of　the　measured　water　body.　Further,　three　characteristic　bands　and　a　retrieval　model　were　established　using　the　exhaustive　method　and　correlation　analysis.　Results　show　that　when　λ1　=　661.63　nm,　λ2　=　693.54　nm,　and　λ3　=　757.35　nm,　the　three-band　factor　[Rrs　-1　(λ1)　-　Rrs　-1　(λ2)]　Rrs　(λ3)　exhibits　a　high　correlation　coefficient　with　the　Chla　concentration　(r　=　0.830).　The　determination　coefficient,　root　mean　square　error,　and　mean　absolute　percentage　error　of　the　model　arc　0.859,　2.446　mg·m-1,　and　32.169%,　respectively,　furthermore,　the　accuracy　is　better　than　that　of　the　band　ratio　and　reflection　peak　models.　These　results　can　provide　a　theoretical　basis　and　technical　support　for　the　Chla　retrieval　in　the　lower　reaches　of　the　Minjiang　River　and　enable　band　selection　for　the　subsequent　retrieval　of　the　Chla　concentration　in　casc-11　waters　using　the　three-band　factor　method.　©　2020　Universitat　zu　Koln.　All　rights　reserved.