The gelation rheology approach was employed to study the weak gel formation of partial hydrolyzed polyacrylamide(HPAM)／phenol／formaldehyde／resorcinol at various concentrations of HPAM and crosslinker under the conditions of the reservoir temperature and salinity．By analyzing the group conversion versus the conversion of the CROSS—linked macromolecules．it was revealed that near the gel point the gelation process was at the early stage of the reaction kinetics

which simplified the study of crosslinking kinetics．Comprehensive data of kinetic process were obtained as a result of the study of the linear viscoelasticity and nonlinear rheological behaviors It is found that the effect of concentrations of HPAM and crosslinker to the gelation and gel intensity is similar

which reflects the common kinetic characteristics of the cmsslinking reaction．After an induced period the complex viscosity rises as an exponential function of time

which is the characteristics of first—order reactions．The critical HPAM concentration for gel formation is around 250 mg／L．In addition

rheological models of complex viscosity and apparent viscosity in steady shear were introduced to describe the gelation process．