The embodiments of the invention disclose a character boundary determining method and apparatus. The method comprises the following steps that: an adjacent line grayscale difference value and an adjacent column grayscale difference value are calculated according to a character grayscale mp; the upper boundary and lower boundary of a character are determined according to the adjacent line grayscale difference value and a preset character height; and the left boundary and right boundary of the character are determined according to the adjacent column grayscale difference value and a preset character width. According to the character boundary determining method and apparatus provided by the embodiments of the invention, the four boundaries of the character can be determined through the adjacent line grayscale difference value, the adjacent column grayscale difference value and the preset character size, and the boundaries of the character can be positioned accurately, and influence on the positioning of the boundaries caused by small stains can be eliminated. The method is simple, does not need additional means to remove stains and is low in time complexity.