Abstract: Poly(N,N-dimethylacrylamide)(PDMAA) and poly(N,N-diethylacrlyamide)(PDEAA) were obtained from the monomers of N,N-dimethylacrylamide(DMAA) and N,N-diethylacrlyamide(DEAA) in aqueous by plasma-initiated polymerization at low temperature. The results showed that the conversion of two monomers increased with post-polymerization time and discharge duration, the conversion of DEAA increased with discharge power, but the power had little influence on the conversion of DMAA, and the optimum mass fraction of the two monomers were 50%. The effect of post-polymerization time, discharge power, discharge duration and mass fraction of monomer on water-absorbing power of polymers were also investigated and found that the optimum post-polymerization time was about 4 h (for PDMAA) and 8 d (for PDEAA) respectively, the absorbencies of both PDMAA and PDEAA decreased with the increasing of discharge duration, and the absorbency of PDEAA decreased with the increasing of discharge power, but it had little influence on the absorbency of PDMAA. The thermal sensitivities of the polymers were studied and found that PDMAA showed a higher critical solution temperature(HCST) within the scope of 20~30℃, while PDEAA showed a lower critical solution temperature(LCST) at 31℃. The highest water-absorbing power of the polymers reached more than 100 g/g, which was 4~10 times that of the polymer synthesized by conventional method.