A　cationic　polysaccharide　(CDCS)　derived　from　dextran　and　chitosan　was　fabricated　by　crosslinking　method　as　an　eco-friendly　flocculant.　The　flocculant　was　characterized　by　thermogravimetric　analysis　and　Fourier　transform　infrared　spectroscopy.　Influences　of　temperature,　pH　and　flocculant　dosage　on　flocculation　efficiency　were　examined.　The　CDCS　presented　enhanced　high　flocculation　properties　in　a　wide　pH　range　conditions.　In　kaolin　suspension,　when　pH　was　in　the　rang　of　3–7,　the　flocculation　efficiency　was　over　96.9%　with　dosage　below　5 mg/L.　In　alkaline　condition,　it　also　presented　a　high　flocculation　efficiency　of　98.2%　(pH = 9)　and　93.7%　(pH = 11)　with　a　low　dosage　of　7　and　17 mg/L,　respectively.　The　flocculation　efficiency　decreased　as　the　temperature　rose　from　10　to　40C.　For　actual　wastewater　treatment,　the　CDCS　flocculant　performed　much　better　than　commercial　polyacrylamide　and　ferric　sulfate.　It　removed　97.7%　of　the　solid　suspended　particles　in　the　wastewater.　The　flocculant　mechanism　study　suggested　charge　neutralization,　adsorption　bridging　and　sweeping　flocculant　mechanisms　were　included　in　the　flocculation　process.　The　flocculant　CDCS　exhibited　a　broad　prospects　for　wastewater　treatment.　©　2017　Elsevier　B.V.