Abstract: The observation of the capillary discharge-pumped Ne-like Ar 46.9 nm soft X-ray laser output was reported under the condition of pure Ar and gaseous mixture of Ar-He, Ar-Ne, Ar-N2 and Ar-Kr. Mixing Ar with an appropriate quantity of He, the laser output was enhanced evidently, and there was an optimum ratio of He in the gaseous mixture of Ar-He, which could be the best for laser output. The experimental results of Ar-Ne, Ar-N2 and Ar-Kr mixture show that Ne, N2 and Kr decrease the laser output. The source research of discharged produced plasma in extreme ultraviolet lithography also mixes an appropriate quantity of He, in order to enhance 13.5 nm.