Elasto-plastic materials, characterized by their energy dissipation and redundant load-bearing capacity, have become a core choice for critical structural design under extreme conditions such as high-load impact, multi-axial stress coupling, and sudden thermal environment changes. To address the numerical simulation demands for elasto-plastic material deformation behavior, this study systematically investigates constitutive theory and numerical algorithms, focusing on the complex mechanical behaviors of elasto-plastic materials. By integrating classical elasto-plastic models (e.g., J₂ flow theory, isotropic/kinematic hardening models) and leveraging the modular architecture and nonlinear solving framework of China's self-developed SABRE nonlinear analysis system, an elasto-plastic constitutive calculation module was developed. This module enables efficient simulation of plastic deformation, stress redistribution, and yield surface evolution under complex loading conditions. The research validated the computational accuracy and engineering applicability of the model through three dimensions: theoretical modeling, algorithm implementation, and engineering application, thereby providing an independent and controllable numerical tool for analyzing nonlinear mechanical behavior in large aerospace structures. Results demonstrate that the module precisely captures the path dependency of materials, laying an important technical foundation for numerical simulation of high-performance materials in China’s aerospace sector.