The effect of raw material ratios on the yield and polymerization reactivity of monomer dimethyldiallylammonium chloride(DMDAAC) was researched in this paper. DMDAAC was prepared by one-step method using dimethylamine, allyl chloride and sodium hydroxide as raw material. The yield of monomer and the intrinsic viscosity of its copolymer DMDAAC-co-AM with cationicity of 10% were used as assessment indexes, and the effect of raw material ratios on them was researched systematically, using the polymerization of DMDAAC-co-AM as template reaction . The results showed that, the raw material ratios had direct influence not only on the yield of DMDAAC monomer, but also on the polymerization reactivity in copolymerization. And the yield calculated based on DMA was 92.7% and the intrinsic viscosity of the copolymer was 12.8dL/g when the optimal raw material ratio was nAC:nNaOH:nDMA =2.08:0.965:1. The products of DMDAAC monomer and coplolymer were characterized by IR and NMR. The results established an experimental basis for the further development of DMDAAC monomer products with high yield, high purity, and high reactivity.