Aiming at the high temperature and high salinity oilfield with loose porosity and easy formation of large channels，the inorganic geopolymer gel plugging agent was prepared by using viscosity increasing agent montmorillonite，crosslinking agent sodium hydroxide，retarder citric acid and main agent fly ash. The gelling speed，influencing factors，temperature and salt resistance，plugging effect，liquid flow steering effect and the effect of profile control and displacement after plugging were studied. The results showed that the gelation rate of inorganic geopolymer gel increased with increasing temperature and concentration of main agent and crosslinking agent. The salinity of solution water had no effect on the gelling effect of inorganic geopolymer gel. The higher concentration of carbonate and bicarbonate in solution water would prolong the crosslinking time of polymer glue. When the permeability of rock core was greater than 18800 × 10-3 μm2，the plugging rate of inorganic geopolymer gel increased with the increase of permeability，and the plugging rate was greater than 90%. Inorganic geopolymer gel had good erosion resistance and liquid flow diversion effect. It could effectively block large pores in high permeability layer and improve the diffluence rate of low permeability core. The longer plugging length of the large pore path or super high permeability zone，the better effect of increasing oil and precipitation was. The plugging effect of inorganic geopolymer gel was better than that of conventional polymer gel and starch glue. It could be used for plugging large pores in high temperature and high salinity oilfield.