The inverse emulsion polymerization of dimethyldiallylammonium chloride (DMDAAC) with acrylamide (AM) was carried out using a redox system as initiator, petroleum ether as oil, and Span-85 and Tween-80 as emulsifiers. The cationic degree of the copolymer increased markedly when AM was fed into the system in batch. The effect of DMDAAC content on the intrinsic viscosity ([η]) and solubility of the copolymer, and the methods of feeding AM on the cationic degree and solubility of the copolymer was studied in this work. The cationic degree of 39.8% of the copolymer was achieved. When the molar ratio of AM to DMDAAC was 4.0, the copolymer with [η] of 10.02 dl/g and the dissolving time less than 15min was obtained. The structure of the copolymer was also characterized by IR spectrum.