Aimed　at　the　raw　water　quality　characterizd　by　low　temperature　and　low　turbidity　in　winter,　high　algae　and　organic　matter　in　summer,　the　combined　process　of　potassium　permanganate　pre-oxidation/dissolved　air　flotation/GAC-sand　filter　was　developed　to　treat　high　algae　water　in　Queshan　reservoir.　Test　showed　that　the　process　could　reach　a　better　result　when　the　dosage　of　potassium　permanganate　pre-oxidation　was　0.3　mg/L,　the　dosage　of　PAFC　was　3　mg/L　(Al3+),　the　dissolved　air　pressure　was　0.3　MPa　and　the　recycle　rate　was　11%.　The　averaged　removal　efficiency　of　TOC,　turbidity,　particulate　matter,　chlorophyll　a　and　blue-green　algae　by　combination　process　were　46.68%,　94.45%,　99.34%,　66.64%　and　95.44%,　respectively.　Odor　level　decreased　with　process　flow,　from　raw　water　level　4　to　effluent　level　1.5.　GSM　treated　by　flotation　unit　was　under　the　detection　limit,　and　the　removal　efficiency　of　MIB　reached　92.47%.　The　removal　rate　of　each　component　of　THMFP,　including　CHCl3,　CHCl2Br,　CHClBr2　and　CHBr3,　were　42.86%,　24.09%,　30.30%　and　37.50%,　respectively.　The　combined　process　has　a　good　ability　to　remove　regular　indices,　algae,　odor　substances　and　precursors　of　disinfection　byproducts.