When carrying out fasteners with twist provisions, the relevant large hexagon bolts must be painted with anti-loosening marks to indicate that the fasteners have been tightened according to the provisions, so as to distinguish them from the fasteners that have not been tightened, so as to prevent the leakage of fasteners during the installation and use process. Identification can be made in the installation process. Play the role of inspection character; In the whole process of the later commodity adoption, the anti-loose mark can also be used as a basis to distinguish the bolt looseness and precaution. Especially in the rail and road transportation industry, the current condition of fasteners immediately endangers the safe driving and personal safety of guests. The marking pen for large hexagon bolt has a special tool for identification, which can quickly generate parallel lines on the top and side of the hexagon bolt head, the top and bottom of the sealing ring and part of the identification on the commodity surface. At once. It reasonably solves the problems of inconvenient and rapid identification, limited bolt position and poor line appearance in the current process. The special tool for the construction of the special tool for locking identification of large hexagon bolts includes the following parts: 1. pen holder; 2. Pen cap; 3. Pencap protrusion; 4. Ink duct cavity; 5. Fully automatic ink core calibration equipment; 6. Ink core sleeve; 7. Ink core cover; 8. Ink core; 9. The top of the ink core cover is highlighted; 10. Torque spring; 11. Concave groove; 12. Theme activity sponge; 13. Punch cavity; 14. Fixed sponge block; 15. Pen cap. When marking, just put the bolt locking line on the outside of the sealing ring, fix the place of the bolt locking line marker on the surface of the electrical product, and then press and hold the bolt locking line. The marking pen is used to make the inner cavity of the bottom end of the pen holder cover the bolt head. The bottom end of the pen holder touches the surface of the electrical product. The marking pen is removed for the whole process of laser marking, and then the bolt can be placed on the surface of the electrical product. The drawing components composed of the top and side of the bolt head, the top and bottom of the sealing ring and the surface of the mechanical and electrical equipment quickly produce parallel lines at one time.