Using industrial monomer solution of methacrylatoethyltrimethyl ammonium chloride(DMC) as raw material, ammonium persulphate(APS) as initiator and tetrasodium EDTA(Na4EDTA) as chelating agent, the preparation of poly(methacrylatoethyltrimethyl ammonium chloride) (PDMC) was researched, based on the method of adding initiator all at once, two-step increasing of temperature for aqueous polymerization. The optimal process conditions were w(DMC)=72.5%, m(APS):m(DMC)=0.20:100, m(Na4EDTA):m(DMC)=0.018:100, and polymerization carried out at 35℃ and then 50℃, each for 3h via the orthogonal experimental method. The intrinsic viscosity of PDMC product and monomer conversion rate under optimal process conditions reached 10.38 dL•g-1 and 98.40% respectively. Structure of the product was characterized via FTIR and 1HNMR spectra. Thus, this results made a foundation to the further research on the preparation of optimization and serialization PDMC products.