The invention discloses an ultrasonic impact surface modification auxiliary titanium alloy diffusion connection method. According to the method, ultrasonic impact is conducted on the surface of a titanium alloy plate, the titanium alloy plate is heated and diffused, so that joints can be tightly combined, and the high-strength connection of a titanium alloy is realized. According to the method, agrain refinement layer is obtained through ultrasonic impact surface modification, the atomic diffusion rate is increased, diffusion connection parameters of the titanium alloy are reduced, and low-temperature diffusion connection of the titanium alloy is realized; and the method is simple and convenient to operate, good in adaptability, high in repeatability, green and energy-saving, and can greatly improve the industrial production efficiency.