The efficiencies of turbidity removal of PDMDAAC flocculant series used to treat the test water of kaolinite have been studied.By the microelectrophoretic technique,the flocculation mechanism of PDMDAAC flocculant series is discussed.Their efficiencies of turbidity removal used with PAC have also been tested.The experimental results show that PDMDAAC flocculant series have excellent efficiencies of turbidity removal,especially to the water with high turbidity.The greater the intrinsic viscosity and cationicity of flocculants,the better the efficiency of turbidity removal.The flocculation mechanism of PDMDAAC flocculant series is the combination of charge neutralization and adsorption bridge formation.Used with PAC,PDMDAAC flocculant series can make the efficiency of turbidity removal better and lower the cost of treatment.