Viscosity of partially hydrolyzed polyacrylamide (HPAM)/aluminum citrate (AlCit) colloidal dispersion gel has been measured in gelation of the system. The result showed that the viscosity of HPAM/AlCit cross-linking system increased with reaction time when the concentration of HPAM is higher

and the final viscosity of the system is higher than the viscosity of HPAM solution with same concentration of HPAM. The viscosity of HPAM/AlCit cross-linking system is decreased with reaction time when the concentration of HPAM is lower

and the final viscosity of the system is lower than the viscosityof HPAM solution with same concentration of HPAM. When the concentration of HPAM lower than critical concentration the HPAM/AlCit cross-linking system formed thin colloidal dispersion gel (TCDG).Under the experimental condition

the critical concentration of HPAM is between 150 and 300 mg/L.When the concentration of HPAM is between the critical concentration and 700 mg/L the HPAM/AlCit cross-linking system formed concentrated colloidal dispersion gel (CCDG).When the concentration of HPAM is higher than 700mg/L the HPAM/AlCit cross-linking system formed bulk gel.