The invention discloses a waste asphalt mixture normal-temperature regeneration modifying agent and a preparation method thereof. Particularly, the waste asphalt mixture normal-temperature regeneration modifying agent comprises the following components in parts by weight: 0-30 part of rubber oil, 30-60 parts of light distillates, 5-10 parts of a polymer, 2-5 parts of a crosslinking agent and 1-5 parts of a surfactant. The regeneration modifying agent is used for producing a regenerative asphalt mixture; the RAP blending rate is high; the blending temperature is low; and the pavement performance of the regenerative asphalt mixture is good.