A simulation code for an electron‐beam‐excited XeF(B→X) laser using Ar/Xe/F2gas mixtures is described. The validity of the code was checked by comparing the computed results to those obtained in a previously reported experiment with a 65‐ns, 1.14‐MW/cm3excitation pulse. Good agreement is demonstrated for sidelight fluorescence, laser waveforms, output power, and energy. Furthermore, the simulation code analysis suggests that the XeF laser can be operated effectively with low‐pressure (<1 atm) Ar/Xe/F2mixtures at room temperature. A maximum intrinsic efficiency of ∼3% is obtained at a total pressure of 0.5 atm. Such a low‐pressure Ar/Xe/F2laser gas mixture would permit operation of a scaled‐up XeF laser system since the intrinsic efficiency is as high as that with conventional high‐pressure (∼3 atm) Ne/Xe/NF3mixtures.