大功率双包层光纤激光器采用分布式多点抽运有利于功率扩展和输出特性的优化。采用数值模拟的方法分别计算了正向多点抽运和反向多点抽运，得出了不同抽运光反射限制和不同的光纤长度条件下抽运点数与输出功率的关系，以及不同抽运点数和不同抽运光反射限制下的光纤最佳长度，并进一步得出，多点抽运时，通过在双包层光纤内包层写入光栅的方法对抽运光进行反射限制可以大大改善光纤激光器的输出特性。这些结论对多点抽运双包层光纤激光器的结构优化具有指导意义。

High power double-clad fiber lasers under multi-point pumping facilitate the increasing of the power and optimizing of the output performance. The forward and backward pump mode is calculated respectively. The calculated results show that pump power reflectivity at the end of the cavity affects the output performance and the optimal fiber length apparently. The relation of the number of pump point and the output power is obtained from the numerical modeling,furthermore,the optimal fiber length as a function of pump point is obtained. The conclusion can be used as reference for the design of the double-clad fiber laser configuration under multi-point pumping.