The spectral response of spatial heterodyne spectroscopy (SHS) is determined by the spectrum property of narrow-band filter.As discussed in previous studies,the symmetric heterodyned interferogram of high frequency waves modulated by SHS and lack of sample lead to spectral confusion,which is associated with the true and ghost spectra.Because of the deviation from theoretical index of narrow-band filter in the process of coating,the boarded spectral response and middle wave shift are presented,and conditions in the theoretical Littrow wavelength made the effective wavelength range of SHS reduced.According to the measured curve of filter,a new wavenumber of zero spatial frequency can be reset by tunable laser,and it is easy for SHS to improve the spectral aliasing distortion.The results show that it is utilized to the maximum extent of the effective bandwidth by adjusting the grating angle of rotation to change the Littrow wavelength of the basic frequency,and the spectral region increased to 14.9 nm from original 12.9 nm.