The proportion of erbium-doped fibre(EDF) length of dual-stage L-band EDF amplifier(EDFA) with cascade structure is optimized,which is done by changing pump power of the second stage under the condition that the EDF length and pump power of the first stage is determined.When the pump power and EDF length of the first stage are 60 mW,and 5.4 m,respectively,the small signal gain is 30.163 4 dB and the noise figure is less than 4.078 dB by optimizing the parameters of the second stage.Compared with other methods,enough high gain could be obtained by choosing proper pump power of the second stage,and this method could make good use of pump power to improve the pump efficiency so the method is more useful.