The invention provides a method for removing a defective packing box with the first line of ink-jet printed characters lacked. The method comprises the steps that a picture of a to-be-detected packing box with the ink-jet printed characters is collected; a designated area is determined according to the positions of the ink-jet printed characters, the Zernike moment in the designated area is calculated, the ink-jet printed character area of the picture is subjected to edge extraction, and image binaryzation is conducted; the characters are straightened; the characters needing to be detected whether the first line is lacked are subjected to the following line lacking detection, specifically, (a) the positions of the characters are found with a template matching method based on the gray value, and the character area is divided; (b) the divided character area in the procedure (a) is subjected to fixed threshold value separating; (c) the 1/4 position of the top of the binarized character area is picked and subjected to projection in the horizontal and vertical directions; and (d) the threshold value X is set according to the length of the first line of the characters, whether the length of the projection in the horizontal direction is smaller than the set threshold value X is judged, and if yes, it explains that the first line is lacked; and the defective packing box is removed.