If you use a custom print style when printing, there will be different line thicknesses. I don't know what your major is. Every major has requirements for every major, because drawings are printed in black and white. Set print lines with different thicknesses to distinguish different objects or different working faces. For example, I am a professional in interior design, and I require that wall lines and furniture lines should be represented by lines with different thicknesses to distinguish walls from furniture. Other majors have requirements for other majors. If you want to print lines with the same thickness, use the default printing style monochrome.ctb (as shown in the figure), and the printed lines are all black with the same thickness. There is an edit button behind the print style sheet. Click the Print Style Manager and adjust the thickness of each color as needed (as shown in the figure), which is why the drawing lines are different.