The dominant seepage channel in the middle and later stages of oilfield development leads to the increase of water cut and the decrease of oil production in oil wells. In order to improve the stability of gel profile control agent in high temperature and high salt harsh reservoirs，based on the phenomenon that the basic crosslinking system composed of low concentration polymer and phenolic crosslinking agent is easy to degrade and dehydrate under the condition of high temperature and high salt，the gel strength and dehydration rate were taken as the main indexes，and the additives that could improve the stability was optimized through semi-quantitative analysis method. The gel strength，temperature resistance and salt tolerance of the obtained gel system were evaluated. The experimental results showed that the addition of antioxidant 1#（compounds containing nitrogen）and complexing agent 2#（organic phosphonate）to the polymer gel system could significantly enhance the stability of the system. Under the condition of salinity of 45 550 mg/L（calcium ion content of 3120 mg/L），the gel system，composed of 0.4% polymer + 0.4%crosslinking agent +1.8% complexing agent 2# + 0.5% antioxidant 1#，had a gel strength of H grade at the temperature of 125 ℃， which was stronger than that of the basic crosslinking system. The gel strength could still reach grade E at the temperature of 140 ℃and the gel dehydration rate was only 5.2% after aging for 180 days，exhibiting excellent temperature and salt resistance. The gel system had good injectivity and plugging performance，the plugging rate being greater than 98%，which was suitable for reservoirs with the temperature of 90—140 ℃，and provided technical support for oil stability and water control in complex and harsh reservoirs.