A CO2-triggered viscosity-sensitive copolymer P(AM-DMAEMA) was synthesized by N, N-dimethylaminoethyl methacrylate and acrylamide with different monomer ratio. The optimal conditions were that: monomer concentration 20%, initiator concentration 0.2%, polymerization temperature 40℃, polymerization time 4.0h. Molecular structure of polymer was characterized by 1H-NMR.Conductivity, Zeta-potential, effective diameter and viscosity experiments were employed to investigate their CO2-triggered viscosity properties and the mechanism of viscosity variation has been found. The results showed that the copolymer presented diversely viscosity variation properties and good CO2 absorb stability．