The scheme of multipath interference reduction based on filter and isolation technology and the scheme of nonlinear coefficient reduction based on hybrid-type optical fiber technology were proposed,which can overcome self-excited phenomenon of remote pumped optical amplifier system with channel associated structure using the traditional 2nd-order pump. Filter and isolation technology can improve multipath interference by placing the filter and isolation unit in the fiber lines. Hybrid structures of ordinary fiber and large effective area fiber can reduce the nonlinear effect when using hybrid-type optical fiber. Theoretical analysis draw a conclusion that multipath interference can be reduced by decreasing multiple reflections of the pump,and nonlinear coefficient can be reduced by increasing the effective area of fiber. The experimental results show that unit the pump power accessed to the remote gain unit is increased by 1.2 dB using filter and isolation unit,and 1 dB using hybrid-type fiber structure with 20 km EX2000 fiber and 80 km G.652 fiber. The research contributes to the realization and application of reducing the effects of self-excited of second-order pump with channel associated structure.