Abstract: The DF and CO2 laser mediums matching for a mid- and far-infrared dual-band laser was studied. Theoretical analysis of the gain distribution of the two mediums shows that, compared with the CO2 laser medium, the peak gain position of DF laser medium is more ahead, and the gain zone length is much shorter. Then a dual-band laser was designed and manufactured, with the position of theCO2 injection orifices adjustable, and the match between the peak gain positions of DF andCO2 laser mediums can be achieved by the position difference of the D2 and CO2 injection orifices. The experiment shows that the design is effective, and the optimum position of the common optical axis of this dual-band laser is 3 mm downstream of D2