Method for improving polymer injectivity

The invention relates to a method for improving polymer injectivity. The method comprises the following steps of: injecting a CTAB (Cetyl Trimethyl Ammonium Bromide) water solution into an injection well as a pre-slug; then, injecting hydrophobic associated polymers for polymer flooding; and finally performing water flooding. Used sacrificial agents are cationic surface active agents of CTAB; the CTAB contains cationic groups, can form a strong adsorption effect with electronegative reservoir minerals, and can also form electrostatic repulsion with cationic hydrophobic groups of the hydrophobic associated polymers at the same time so as to reduce the mutual effect with the polymers; the goals of isolating the polymers from a reservoir and reducing the adsorption quantity of the polymers in a near wellbore zone are achieved; meanwhile, the use cost of the polymers is reduced; the used acrificial agents have good compatibility with formation water and polymers; and the wide application to the reduction of polymer adsorption in the near wellbore zone in the oil flooding process relevant to oil field polymers can also be realized.