The polyvinyl alcohol-glutaraldehyde gel system was investigated in this work. The gelation kinetics under oil field environments and effects on the structures and properties of the gels formed were discussed. The basic characteristics of this gel system were determined. The fundamental data during gelation were obtained and application of the gel system for the tertiary oil recovery was evaluated. Under the experimental condition, among the gelation time t, initial pH of the system, and glutaraldehyde concentration x, there exists the relation ln t(pH, x) = 2.35pH - 0.85 ln x - 10.91 It is conspicuous that the gelation of this gel system is less sensitive to hardness and salt contents; the gels formed under the relevant condition were quite stable. Thus, the application of this gel system for tertiary oil recovery under hostile environments is very promising.