The invention discloses a method for modification of rubber in crumb rubber concrete. The method comprises the steps of 1, preparing acidic potassium permanganate treating fluid, wherein the mass of potassium permanganate accounts for 0.5-3% of the total mass of the treating fluid, and nitric acid accounts for 0.5-6% of the total mass of the treating fluid; 2, soaking rubber particles in the acidic potassium permanganate treating fluid for 5-50 h, and filtering, cleaning and then drying the rubber particles. After being modified by means of the acidic potassium permanganate treating fluid, the wettability of the rubber particles is improved remarkably, the contact angle is reduced to 67.1 degrees from the original 80.3 degrees, and the surface polarity of the rubber particles is improved through the action between acidic potassium permanganate and the rubber particles; the peak intensity of the surface hydroxyl group or ether group of the modified rubber particles is improved remarkably, the carbanyl group or C=C bond in rubber can be partially oxidized into hydroxyl or carboxyl by potassium permanganate, and then the polarity of rubber macromolecules is improved; bonding force and mechanical engaging force between the modified rubber particles and cement paste are higher, and compressive strength and breaking strength are high.