<p>Due to the pollution and depletion issues associated with fossil fuels, renewable biomass energy has emerged as a critical alternative. The thermal conductivity of biomass is an important parameter in the transportation, storage, pretreatment and conversion of biomass energy. In this study, three categories of biomass samples (herbaceous materials, woody materials and fermented materials) were crushed into small particle and compressed discs to measure thermal conductivity. Research shows fermented materials exhibit the highest thermal conductivity (averaging 0.0856&#xa0;W m⁻¹&#xa0;K⁻¹ as tapped powder; 0.1904&#xa0;W m⁻¹&#xa0;K⁻¹ as discs) and the highest tapped density (averaging 617.3&#xa0;kg m⁻³) among all biomass samples. Beyond total porosity, particle morphology (sphericity and aspect ratio) is identified as a governing factor influencing heat transfer pathways by affecting inter-particle contact area and the continuity of the solid matrix. Based on the series–parallel model, we develop a modified version that incorporates the sphericity, aspect ratio and total porosity of the particles to determine the series and parallel weights. The model achieves a low root mean square error of 0.0084&#xa0;W m⁻¹&#xa0;K⁻¹, which represents a significant reduction of approximately 70% compared to traditional models (parallel, series and Maxwell-Eucken models).</p> Graphical Abstract <p></p>