Using homogeneous pump, and by controlling the reaction temperature in stages, dimethyl diallyl ammonium chloride (DMDAAC) monomer was synthesized in one step using dimethy lamine, allyl chloride and liquid caustic soda as starting materials. In the vacuum distillation purification process, the pH value of the crude DMDAAC solution was adjusted via a syringe pump adding liquid caustic soda. The results showed that the use of homogeneous pump improved the materials mixing, shortened the dropping time of allyl chloride from 5h to 3.5h, and prevented the occurrence of side reactions. The yield is up to 91.5%, which is 21.11% higher than that in the traditional one-step method. And the polymerization performance is also studied. Molecular weight of homopolymer can reach to 125,000. The intrinsic viscosity of the polymer product increased from the original value 1.19 dl•g-1 to 2.80 dl•g-1. The monomer conversion rate increased from 90.08 % to 99.23 %. The 20 L bench-scale research for this technology have been done.