Abstract: The distribution behavior of bubbles in consideration of casting speed and electromagnetic braking in a slab continuous casting mold was investigated by the method of sampling statistics. The effects of electromagnetic braking and casting speed on the size, number and distribution of small bubbles were analyzed in detail. Experimental results show that bubbles with the diameter less than 0.1 mm account for 57%, 0.1-0.5 mm for 42.5%, and bigger than 0.5 mm for 0.5%. The deeper the subcutaneous distance is, the smaller the bubble size is. The number of bubbles in the narrow side is 50% more than that in the 1/4 position, and the number of bubbles in the 1/4 position is the least. With increasing casting speed, the size of bubbles decreases and the position of clusters moves from 9 to 12 mm in the slab subsurface at the 1/4 position and the narrow side, but bubbles gather at 3 mm of subsurface at the low and high casting speeds. When electromagnetic braking is applied, the size of bubbles becomes big in the center, but small in the 1/4 position and the narrow side, and the number of bubbles overall declines, significantly the number of cluster bubbles.