According to the exploration and field test results, the reservoir presents high temperature (96°C) and high salinity (77954.03 mg/L) features; therefore, it is necessary to find proper plugging agent that can be used in these reservoirs to enhance oil recovery. In this paper, three kinds of polymers are studied and high temperature resistance as well as relative parameters are tested. According to the testing results, we make a preliminary determination that concentration of polymer solution is 2500-3500mg/L. However, due to the high reservoir temperature, APP5 polymer degrades severely. In view of the polymer degradation problem in high temperature, 2.7% chromium acetate is added into the APP5 solution (Cr³⁺/APP5=1/60), and the retarder is added at the same time. The stability of this new plugging agent is then tested. The results show that, when the shearing time reaches 60s, plugging agent remains at a high level of 24600mPa•s, and the static adsorption of APP5 remains at a low level of 0.36-0.38mg/g. As a consequence, the Cr³⁺/APP5 plugging agent can meet the production requirements in reservoirs. Based on results of laboratory physical simulation experiment, plugging efficiency of this plugging agent is higher than 75%, and injected slug size of Cr³⁺/APP5 plugging agent is 0.3PV.