Abstract: A gear unit applies to engaging a ratchet wheel for co-operation, wherein the body material of the gear unit is chose high-density steel through heat processing for enhancing hardness, such as medium carbon steel, high carbon steel, or alloyed steel, and made through continuous multiple cold forging and punching and heat processing; the gear body of the gear unit includes a junction matching the ratchet wheel profile and forming an external tooth through cold forging and punching, and the tooth shape matches the ratchet tooth of the ratchet wheel to engage the ratchet wheel; by way of using the special steel through the process of continuous cold forging and punching and heat processing, the internal structure of the gear unit is dense compaction, so as to improve the mechanical properties, thus the ratchet wheel wrench using the gear unit will have excellent operating performance and long service life.