The invention discloses a method for removing transverse crack defects of a continuous casting billet corner of boron steel. The method comprises the steps of: adopting a whole argon blowing mode for smelting of a converter; in refining, finally, adjusting boron alloying after finishing adjustment of other alloy ingredients and temperature; controlling N content of molten steel in a casting process to be less than or equal to 50ppm and B content to be less than or equal to 80ppm; and controlling the strength of secondarily cooling of the continuous casting billet to be a water ratio being less than or equal to 0.90/kg, wherein the ratio of cooling water quantity of the secondary cooling at continuous casting stages in the total water ratio is 15-20% in a foot roller area, 15-22% in a vertical section area, 15-40% in an arc section area and 3-5% in a straightening area; and the narrow-surface temperature of a continuous casting billet in a bent area is more than 1000 DEG C, and the narrow-surface temperature of the continuous casting billet in the straightening area is more than 870 DEG C. According to the method for removing the transverse crack defects of the continuous casting billet corner of the boron steel, the nitrogen content in the molten steel is effectively reduced; the transverse cracks of the corner are removed; and the corner cut loss and the heat loss are avoided.