The change of spectral matching factors between photo cathode and reflecting spectrums of scenes is analyzed,when the laser aids system is used. Its expression is given,and the character and significance of the expression are analyzed. The spectral matching factor is calculated between the Super Second Generation Photo Cathode(New S₂₅,Super S₂₅₁,Super S₂₅₂) and scenes by the laser. And the results are 0.833,0.72 and 0.56,which proves the laser(λ=850 nm) is reasonable. The character of matching factor under laser aids is discussed and analyzed. All of above is with practical value in the evaluation of visual range of night vision systems when the laser aids system is used.