The isometric line ruler has been lengthened, widened and thickened as a whole, which is comfortable and portable. The precise size of the overall engraving line is up to 80mm, and the double fixed slide rails are precisely controlled. The top nut controls the position of the marking needle, and the right end nut adjusts the position of the vernier scale. The tungsten steel triangular head marking ruler is sharp and wear-resistant, the marking is smooth, and the operation efficiency is improved.