3-[N,N-Dimethyl-N-(methacryloyloxyethyl) ammonium] propane sulfonate (DMAPS) was synthesized from methacryloxy ethyl dimethyl amine (DM) and 1, 3-propane sultone. Amphoteric polyelectrolyte poly3-[N,N-dimethyl-N-(methacryloyloxyethyl) ammonium] propane sulfonate (PDMAPS) , which was used as dispersant for silica, was successfully synthesized by the bulk free radical polymerization of DMAPS in water solution using ammonium persulfate as the initiator and sodium hypophosphite as chain transfer agent, and used as dispersant for silica. DMAPS and PDMAPS were well characterized by FTIR, 1HNMR and GPC. Moreover, the influence of different reaction condition on the PDMAPS’s performance was conducted by the method of single factor experiment and orthogonal experiment. In order to achieve the lowest viscosity and smallest mean particle size (d50) for the silica, the optimum preparation condition were obtained as follows: the reaction temperature is 75 oC, the reaction time is 3h, the adding amount of initiator is 1.0% of the monomer, and when the adding amount of PDMAPS is 0.8% to silica, the results showed that the d50 of the dispersed silica reduced from 21.193μm to 0.449μm, which indicated that PDMAPS can be used as potential dispersant for silica.