The gel system composed of polyacrylamides and zirconium acetate was investigated in the paper. The change of the viscosity of the gel system was investigated in the crosslinking reaction process. The reaction process could be divided into three successive steps: induction period, rapid cross-linking period, and stabilization period. The gel formed in a 3-dimensional network structure was confirmed by environmental scanning electron microscopy (ESEM). With the increase of polymer concentration and crosslinker concentration, reaction temperature and salt content, the gelation time reduced, and the gel strength increased. Three salts were arranged according to their influence on gelation system in following order: CaCl₂ > MgCl₂ > NaCl. A solution with pH value of 7-8 was the best suitable for the gel system. the gel system was suitable for the reservoir with the temperature below130℃.