Abstract: Composite materials have wide application prospects in high-end equipment, such as aerospace, watercraft, high-speed train and so forth fields, in view of their advantages of lightweight, high strength, and performance designability. However, current commercial software is mainly focused on single-scale functions, like digital design of composites, overall property prediction, macroscopic response simulations, or structural optimizations. Specifically, when these software is combined to perform multi-scale simulation or optimization problems, including version incompatibility, inconsistent data format and so forth are prone to occur, which makes it quite difficult to satisfy requirements of integrated and innovative design of composite components in high-end equipment. In this paper, a cross-system platform SWJTU-CAX for developing design-simulation-optimization software of composites and structures was designed and developed by combining object-oriented method with modular design ideas. The platform was programmed using cross-system development environment QT and data visualization library VTK as main tools, and adopts data layer, logical processing layer, and presentation layer as overall architecture to deal with core difficulties of data management and processing, functional organization and module expansion, efficient access and visualization of large-scale data in whole process of composite and structure designs, cross-scale simulation, performance prediction, parallel computation and optimization designs. Meanwhile, code organization and functional testing of SWJTU-CAX were carried out using modular approach combined with CMake tool. With help of XML file management, addition and removal of required functional modules are realized conveniently on the proposed platform. Furthermore, rapid integration and expansion of composite and structural design, simulation, optimization and other functional modules can be implemented rapidly. Finally, ceramic composites and components were taken as illustration, and specific software was developed based on SWJTU-CAX platform to realize digital modeling, cross-scale property prediction, response simulation, and integrated optimization design functionals of ceramic composites with arbitrary weaving forms. Feasibility of cross system platform architecture, data organization, and project management method was thus verified. Development of SWJTU-CAX platform provides a powerful tool for in-depth exploration of cross scale failure mechanism of heterogeneous materials and on-demand design as well as service safety evaluation of equipment composite components. Moreover, it provides technical ideas and references for domestic industrial software architecture and research & development.