This paper aims to develop an autonomous structural topology optimization software with high openness and flexibility. Based on the foundational platform of the aerospace structural analysis software SABRE system, it systematically elaborates the layered and plugin-integrated architectural design methodology. From the perspectives of both developers and users, this paper presents the implementation methods for software functional modules and solution processes. Building upon the classic variable-density topology optimization theory, it outlines the design and implementation process of topology optimization functionality within the SABRE system. Numerical examples are employed to verify the software's functional validity and engineering applicability, further demonstrating the openness of SABRE's architecture and the flexibility of its solution process organization. This work provides valuable reference for efficiently integrating new algorithms and modules in structural analysis and optimization into autonomous software platforms.