Due to the application of excimer lasers, it is necessary to control the output spectrum of excimer laser. Control spectrum contain narrowing bandwidth and stable output of center wavelength. The familiar mean of line-narrowing is using combination of beam expander prisms and grating to narrow the bandwidth of laser. With the combination of fused silica prisms and grating controlling the ArF excimer laser, the line-narrowed excimer laser of the output spectrum of light source is 0.957 pm. Theory analysis and experiments indicate that with a high transmission in ultraviolet (UV), fused silica prisms can reach the same effect in line-narrowing with the CaF2 which is often used now. At the same time, the cutting way of isoceles triangle prisms can be made more exactly, less costing and should be applied more widely.