With the expanding scope of space operations and increasing types of space missions, the space robotic arm starts to complete space missions in a new working mode of cascade. The method constructs the configuration optimization index of the cascade combiner according to the characteristics of the load operation task, then improves the solution method of the inverse solution of the velocity level of the cascade robot arm in the iterative process of the genetic algorithm for the problem of the high degree of freedom of the cascade robot arm, designs the configuration optimization process, and finally proposes the numerical optimization of the configuration of the space cascade redundant robot arm under the load operation task scenario based on the genetic algorithm. Finally, a numerical optimization method based on genetic algorithm is proposed for the cascaded redundant robotic arm to ensure the accuracy and accessibility of the task and improve the flexibility of the operation in the load operation scenario. The feasibility of the method is verified by simulation calculations, and the research method and results can guide the configuration planning of cascade assemblies in on-orbit service, which has strong engineering application value.