Temperature is a key factor limiting the degradation of polymer gel. Aiming at the blockage caused by polymer gel in low temperature reservoirs，the oxidation ability of persulfate was improved by low temperature activation using persulfate as oxidation reducer. First，the activator（TA）was prepared from copper sulfate hydrate and tetrasodium iminosuccinate. Then the quenching experiment and the radical test were used to analyze the degradation mechanism of the polymer gel. Finally，the effect of persulfate concentration and TA concentration on the degradation of polymer gel at different temperature was studied. The formula of activation system was optimized. Meanwhile，the corrosivity of the system was also evaluated. The results showed that TA activated persulfate could rapidly degrade the polymer gel at 35 ℃. The superoxide anion radicals were the main active radicals in degradation reaction. With the increase of persulfate concentration，the degradation rate increased，but the concentration of TA had the optimal value，and the temperature increase could accelerate the degradation of gel. Compared with other polymer plugging removers，TA activated persulfate could rapidly degrade polymer gel with mild corrosion. At low temperature，the system composed of 0.10 mol/L sodium persulfate and 0.12 mol/L TA had better degradation effect than other conventional polymer flooding reservoir plugging agents.