To simplify the dosing steps of microbioflocculants and eliminate the secondary pollution arising as the using of flocculation aid, 3-chloro-2-hydroxy-propyl-trimethyl ammonium chloride (CTA) was employed to modify the negatively charged microbioflocculants (~-54mV) so as to obtain the positively charged cationized flocculants in this paper. The results showed that the mole ratio of CTA/NaOH was the major influence factor for successful cationization of microbioflocculants. Optimal cationization conditions of microbioflocculants were:10g microbioflocculants, 0.015mol CTA, the mole ration of CTA/NaOH=0.95 and 20% (m/m reaction system) water, reacting at 80℃ for 2h. Under the optimal conditions, Zeta potential of the obtained cationized flocculants reached +16mV, flocculating activity of the obtained cationized flocculants increased from 60.5% which was the maximum flocculating activity of the unmodified microbioflocculants to 91%. Characterization results of the cationized flocculants showed that, the cationized group has indeed introduced into the original microbioflocculant during the cationization reactions, but did not change its carbon skeleton structure, so the ratio of the large molecular weight in the cationized flocculants is increased. And meanwhile the large amount of cationized group increased the crystalline and the solubility of the modified flocculants. The modified flocculants could also be applied for removing microcystis aeruginosa, and its removing rate could exceed 98% when the concentration of cationized microbioflocculants was 40mg/L, while the unmodified microbioflocculants have no effect on the removing of microcystis aeruginosa.