Abstract: A new method of user-defined linetype is put forward to design linear symbol.This method can solve the drawing problems and improve the drawing speed.In addition,with respect to the serious distortion of symbol on the vertices of line,such as symbol breakage,symbol intersection,the methods of symbol self-adaptability and double affine transformation are used to manipulate the distortion,which promotes the visual effect of symbol and meets the need of linear symbol with different styles.