Carbon dioxide laser

The invention provides a carbon dioxide laser which comprises a laser generating module, a window lens and a laser output light path. The laser generating module is used for generating lasers by using carbon dioxide, the window lens is connected with the laser generating module and used for allowing the lasers coming from the laser generating module to permeate through, the laser output light path is connected with the window lens, an inert gas output device is arranged at a position close to the surface of the window lens. Since the inert gas output device is arranged at the position close to the surface of the window lens and can purge the surface of the window lens, surface pollution of the window lens of the carbon dioxide laser can be prevented or slowed down, and accordingly, the service life of the window lens of the carbon dioxide laser is prolonged.