Abstract: Micro-truss material has the characteristics of strong load-bearing capacity, high light-weight degree and large design space. It’s a new kind of material with great potential in the application of aeronautical structure design. It’s an important way to design light-weight structures by filling micro-truss material, and the powerful topology optimization technology provides light-weight design ideas. In this paper, taking a typical aeronautical frame-beam structure as the research object, a structural topology optimization design method with micro-truss filling was proposed. Firstly, the mechanical performance of the original design was evaluated to obtain the performance constraint indexes for next topology optimization. Secondly, the frame-beam structure was redesigned in the design domain without sacrificing mechanical performance by topology optimization technology to obtain the initial light-weight model. Finally, taking the initial light-weight model as the research object, secondary topology optimization was used to obtain the final frame-beam model with micro-truss filling. Compared with the initial light-weight model, the weight of the final frame-beam model with micro-truss filling has reduced by 8.6%. Compared with the original model, the weight of the final model has reduced by 17.6%. This example has proved the effectiveness of the design method, and has also proved that the introduction of micro-truss material can greatly improve the light-weight degree.