Abstract: The influences of oil sands,water quality and dissolved oxygen content on long-term stability of polyacrylamide solutions at high temperature (75℃) are investigated through laboratory experiments. It is found that oil sands can slightly lower solution viscocity in the first few days and then keep it to be higher later no matter the temperature is high or low,Crude oil have no negative effects on the stability of polymer solutions,pure sands have similar effects as oil sands and can improve solution stability which is further improved by temperature field,and the presence of oil sands raises the tolerance limit of polymer solutions to dissolved oxygen.The combination of oil sands, formation water and temperature field counteracts the negative effects of dissolved oxygen and high temerature, and largely improves the stability of polymer solutions, thus are beneficial to the success of pilot polymer flooding.