The invention provides a low noise index erbium doped fiber amplifier design optimization method. The low noise index erbium doped fiber amplifier design optimization method is characterized in that the variance DeltaIL(lambda) of an intermediate-stage loss IL is designed to be wavelength-dependent, and DetalTilt: DeltaTilt=DeltaILline(lambdan) - DeltaILline(lambda0) is defined, and DeltaTilt causes a change in GT, and the variance is DeltaGT1; when the external gain remains unchanged, the change in the intermediate-stage loss IL causes the GT to change, and the variance is DeltaGT2; when DeltaGT1 + DeltaGT2 = 0, the GT remains unchanged; and when DeltaTilt < 0, a noise index NF can be optimized following decreasing of the gain, unchanging of the GT and no significant deterioration of GR.