Preparation method of polymer with ultrahigh salt resistance

The invention provides a preparation method of a polymer with ultrahigh salt resistance. The preparation method comprises following steps: (1), acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, functional monomers, a cosolvent, sodium carbonate and a defoaming agent are added to deionized water in sequence, and a uniform solution is prepared; (2), the solution prepared in step (1) is cooled to 14-16 DEG C, nitrogen is introduced to remove oxygen, a chain transfer agent, a chelating agent and azodiisobutyronitrile are added in sequence, an oxidizing agent and a reducing agent are added after 10-20 minutes, when the solution becomes sticky and the system temperature is increased by 3 DEG C, nitrogen introduction is stopped, sealing and thermal-insulation polymerization are performed, and after the system temperature is increased to the highest temperature, the temperature is not increased, that is, the polymerization reaction is finished; materials obtained after the polymerizationare subjected to hydrolys