The invention discloses a method for detecting concentration of a polymer for oil displacement. The method comprises the following steps: (1) preparing the standard aqueous solutions of the polymer of at least five different concentrations; (2) respectively adding a digesting agent and aids into the standard aqueous solutions of the polymer, heating to carry out a digestion reaction, cooling, adding an acid solution, and respectively measuring the absorbance of the digested standard aqueous solutions of the polymer and the reference at the wavelengths of 220nm and 275nm by utilizing an ultraviolet spectrophotometer; respectively calculating the corrected absorbance of the standard aqueous solutions of the polymer and the reference, and drawing a standard curve by taking the concentration of the standard aqueous solutions of the polymer as a horizontal coordinate, and taking the difference of the corrected absorbance of the standard aqueous solutions of the polymer and the corrected absorbance of the reference solution as a vertical coordinate; (3) taking a to-be-measured polymer sample for oil displacement, and repeating the step (2), thereby obtaining the concentration of the polymer. The method disclosed by the invention is easy and rapid to operate, batch detection can be realized, the cost is reduced, the precision and accuracy are high, the equipment is small and portable, and the method has on-site oilfield application prospects.