The transverse shrinkage and angular distortion of line heating have been studied using a theory of torus model and experiments of laser forming. The similarity law was applied for changing from several meters scale of the forming plate in the field to several millimeters scale of specimen. The experiments of laser forming were done under conditions of changing width, thickness, radius of width of plate, line heating length and travel speed. The following results were derived: (1) The radius of width does not almost affect the angular distortion. (2) The conditions of triangle heating are given by both the heating length being above 0.35 times as long as the plate width and the change of travel speed being above three times. (3)The radius of plate width does not affect the transverse shrinkage. (4)The equation of heat input for obtaining the planned transverse shrinkage was proposed.