This paper introduces an improved Halpin–Tsai model to predict the mechanical, thermal, and electrical properties of silicon-carbide-reinforced polypropylene (SiC/PP) composites. The model considers the influence of porosity and silicon-carbide volume fractions, deriving relationships between material property shape factors and aspect ratio, silicon-carbide volume fraction, and porosity. The improved model's predictions show errors of 4.00% for mechanical properties, 2.13% for thermal properties, and 2.24% for electrical properties compared to finite element analysis. The study demonstrates that the improved Halpin–Tsai model can effectively predict the properties of SiC/PP composites, aiding in their design and optimization. The research highlights the impact of porosity and silicon-carbide volume fraction on the mechanical, thermal, and electrical properties, providing valuable insights for enhancing the performance of these materials.This paper introduces an improved Halpin–Tsai model to predict the mechanical, thermal, and electrical properties of silicon-carbide-reinforced polypropylene (SiC/PP) composites. The model considers the influence of porosity and silicon-carbide volume fractions, deriving relationships between material property shape factors and aspect ratio, silicon-carbide volume fraction, and porosity. The improved model's predictions show errors of 4.00% for mechanical properties, 2.13% for thermal properties, and 2.24% for electrical properties compared to finite element analysis. The study demonstrates that the improved Halpin–Tsai model can effectively predict the properties of SiC/PP composites, aiding in their design and optimization. The research highlights the impact of porosity and silicon-carbide volume fraction on the mechanical, thermal, and electrical properties, providing valuable insights for enhancing the performance of these materials.