Abstract: Powder metallurgy, as an efficient near-net-shaping technology, has significant application value in fields such as aerospace, automotive manufacturing, electronics, and medical industries. However, traditional powder metallurgy process design and optimization primarily rely on empirical trial-and-error methods, which are not only time-consuming and labor-intensive but also struggle to meet the demands of high-performance components. In recent years, the rapid development of numerical simulation technologies has provided critical support for the digital design of powder metallurgy processes. This paper summarizes numerical simulation techniques for powder metallurgy compaction and sintering processes, with a focus on multi-scale modeling methods for compaction densification and sintering microstructure evolution. During the compaction stage, the paper analyzes the applicability and limitations of three types of constitutive models: empirical models, plasticity models for sintered compacts, and generalized plasticity models, revealing the regulatory mechanisms of relative density on the mechanical behavior of powder compacts. In the sintering stage, a comprehensive kinetic framework covering the initial, intermediate, and final stages is summarized, elucidating the microstructure evolution laws dominated by diffusion mechanisms. Finally, future development directions such as multi-physics coupling modeling and machine learning-assisted optimization are envisioned, providing theoretical support and technical pathways for the digital design of powder metallurgy processes.