Abstract: The flash beam blasting characteristics in the AC flash butt welding of rail was analyzed quantitatively by the combination of high-speed photography technology and infrared temperature measurement system. The results proved that for the AC flash butt welding, the accelerate flash stage had the highest flash frequency of 46.93, and the pulse flash stage presented the lowest flash frequency of 11.07. Moreover, the strongest flash intensity of 0.009 2 existed in the continuous flash stage and the pulse flash stage had the weakest flash intensity of 0.003 8. For the flash heating factor, the pulse flash stage with the highest flash frequency accumulated amount of heat. However, owing to the vaporization to take away the heat, the accelerate flash stage had the lowest flash intensity. For the flash uniformity, the most uneven flash and even flash generated in the flash flat stage and pulse flash stage, respectively. It proved that the optimal micro-smoothness of the end faces appeared in the pulse flash stage.