Abstract: This paper presents a method for improving the performance of linear symbol by considering the variation of line unit.In this method, the members of line unit should be divided into two kinds:flexible ones and rigid ones.Some members can be destined for the particular position on the symbol.In the process of drawing, size of line unit may be changed and line symbol should deal with some abnormal cases.By using this method for designing linear symbol, some usually complex and difficult problems can be solved.