Based on the discrete algorithm of rate-equation,the gain dynamic of Er3+/Yb3+ co-doped double-clad fiber amplifier was presented.The changes of power excursion with dropped channels,as well as the results of different gain control methods were investigated.The results show that the level of power excursion increases with the number of dropped channels.Under pump control,the change of pump power increases with the number of dropped channels and the time of suppressing power excursion increases as well.While...