Abstract: High effective flocculation strain geotrichum candidum, penicillium, erythromycin, and yeast were isolated from potato starch waste water. Choosing kaolin suspension as the research object, authors had carried out flocculation experiments on single strain and mixed strains, respectively. These cultivation conditions were optimized and the flocculation rate, COD values, and BOD5 values were determined in this experiment. The effective flocculation method was found was to be with geotrichum candidum and under the flocculation rate of 92.39%, when single strain was flocculated. Cultivated in waste water medium, the best flocculation effect of geotrichum candidum was achieved under the optimized conditions, which were the temperature of 35℃, the pH of 5.0, and a fermentation time of 5d. The removal efficiencies of COD and BOD5 were 90.32% and 86.0%, respectively. In the case of the flocculation of mixed strains, the best flocculation effect was realized with the combination of geotrichum candidum and penicillium, with a flocculating rate at 92.47%. The removal efficiency of COD and BOD5 were 93.21% and 90.15%, respectively.