Abstract: Activated silica acid is an important raw material for both producing silica acid coagulant and new inorganic metallic ion-containing high-molecular polysilica acid coagulants.Rate of polymerization of the activated silica acid is affected by the speed of stirring markedly.And there are few reports in this field in China.Based on several direct and indirect me-thods,such as PCS,turbidity,and viscosity,the change of morphology of activated silica acid during its polymerization process were monitored and characterized.Results showed that the quicker of stirring speed was provided and the quicker of polymerization rate of activated silica acid was obtained,however,the smaller of effective diameter as well.Selecting the still condition to prepare activated silica acid was beneficial to the formation of higher molecular weight,higher viscosity,and higher turbidity polysilica acid,and it was more conducive to bringing the adsorption and bridge functions of polysilica acid into play.Results provided an experimentation basis for preparation of high-efficient coagulants.