Water-in-water type cationic polyacrylamide (CPAM) emulsions with low viscosity, high polymer content and high stability were synthesized by radical copolymerization of acrylamide（AM）,Methacrylatoethyl trimethyl ammonium chloride (DMC) and N,N′-methylenediacrylamide (MBA) as the monomers in the polyethylene glycol 20000(PEG 20000)solution. The effects of PEG2000,DMC, initiator(KPS),polymerization temperature on viscosity were studied; Kaolin flocculating tests shows：Under the condition the temperature is 40℃~50%,the reaction time 5 hours ~8 hours, w(PEG20000)=80%、w(KPS)= 0.8%,when w(MBA）=0.3%，w(DMC)= 10%，the product has better flocculating performance and good stability. Transmission electron microscope（TEM）shows spherical droplets and stripe shape droplets dispersed throughout aqueous dispertion.Infrared spectrum shows the synthesized polymer chain contents AM chain unit 、DMC chain unit and MBA chain unit.