The transfer of output spectrum of traditional hydrogen fluoride (HF) laser to long wave and high efficient output of spectral lines, whose wavelength is more than 2.87 μm, is realized by optimizing structure parameters and adjusting reaction system formula. The results of experiment and theory show that the proportion of 2P8 spectral line decreases ceaselessly, and the ratio of spectral lines, such as 1P10, 2P10, increases gradually as the optical axis moving from 11 mm to 15 mm. Moreover, the output spectra of HF laser compete intensely in self and different bands, and cascade effect appears among them. All results extend the utility output spectrum range of HF laser, and make some long wave spectral lines output efficiently, which has an important guiding significance to research and application of the line selected techniques in HF laser.