1. A method for generating typographical line adapted to generating a plurality of typographical lines of a line of printing words, wherein the line of printing words comprises a plurality of printing characters, the method comprising: (a) scanning the line of printing words and labeling a first edge and a second edge of each printing character in the line of printing words; (b) extracting a first edge reference point of the first edge and a second edge reference point of the second edge of each of the printing characters, respectively; (c) using a least square method to obtain a first straight line asymptotic to the first edge reference points; (d) using the first straight line as a first base line to calculate a vertical distance between each of the second edge reference points and the first base line; (e) using a group converging algorithm to divide the second edge reference points into a first group and a second group according to the vertical distances; (f) using the least square method to obtain a second straight line and a third straight line asymptotic to the first group and the second group of the second edge reference points, respectively; (g) using the second straight line or the third straight line obtained from corresponding first group or second group that has the most reference points as a second base line to calculate a vertical distance between each of the first edge reference point and the second base line; (h) using the group converging algorithm to divide the first edge reference points into a third group and a fourth group according to the vertical distances; (i) using the least square method to obtain a fourth straight line and a fifth straight line asymptotic to the first edge reference points of the third group and the fourth group, respectively; and (j) using the second straight line, the third straight line, the fourth straight line and the fifth straight line as the typographical lines of the printing word line.