Slant correction for billet characters is primary and critical step of the recognition of steel billet characters. Character positioning is not accurate when the billet characters are inclined. To solve this problem, this paper presents an algorithm of slant correction for billet characters using height feature of characters. Characters are linearly arranged, using this feature, the angle between the horizontal direction and the base line can be calculated, then the sloping billet characters can be corrected. Experimental results show that the proposed method can correct sloping characters accurately. Compared with the traditional algorithm of slant correction for billet characters, the proposed method can obtain better results.