To　harvest　microalgae　in　a　high　concentration　and　efficiency　way　limits　the　scale　development　of　microalgae　industry,　so　researching　an　efficient,　environmentally　friendly　and　economical　technology　on　microalgae　harvesting　is　of　great　significance　for　microalgae　harvesting　areas.　Cationic　starch　flocculant　is　a　new　technology　of　microalgae　harvesting.　In　microalgae　flocculation　experiments　by　CSF(DS=0.32),　taking　flocculation　efficiency　as　the　target,　examining　the　influence　of　stirring　time,　stirring　speed,　settling　time　and　pH　value　of　the　solution　microalgae.　And　the　safety　and　economy　of　CSF　was　assessed.　The　results　show　that　the　optimum　flocculation　condition　was　as　follows:　stirring　time　10　min,　stirring　rate　200　r/min,　sedimentation　time　20min;　The　microalgae　flocculation　efficiency　is　not　affected　by　the　pH　value　of　microalgae　flocculation　system;　CFS　does　not　affect　the　physiological　activity　of　microalgae　and　is　a　safe　and　sound　flocculant;　The　flocculation　cost　for　harvesting　1　kilogram　microalgae　was　0.2　yuan　by　using　the　prepared　CSF　(DS=0.32),　which　meet　the　demand　of　economy　in　microalgae　biodiesel.　©　2016,　Editorial　Office　of　Journal　of　CIFST.　All　right　reserved.