<p>Lignocellulosic biomass is a globally abundant renewable resource with diverse applications in energy and chemical production. It can be directly combusted or processed into solid fuels, bio-oil, biochar, and various value-added chemicals. However, plant growth inherently accumulates inorganic matter containing alkali/alkaline earth metals (AAEMs), transition metals, P, S, Cl, and other elements. These inorganic constituents frequently pose challenges to downstream processing, affecting product quality, yield, and equipment reliability. This review systematically evaluates the critical role of lignocellulosic biomass de-ashing technology in enabling sustainable bioresource utilization. It begins by establishing the necessity of biomass energy development and the technical requirements for ash removal in producing high-value products. Subsequent sections provide a comprehensive analysis of biomass structure-property relationships, state-of-the-art de-ashing methodologies (including water, inorganic acid, and organic acid treatments), and advanced analytical techniques for ash characterization. Particular emphasis is placed on mechanistic insights into ash-mineral interactions and process optimization strategies. The concluding section synthesizes recent advancements in de-ashing technologies, highlighting their potential to enhance biomass conversion efficiency and reduce operational constraints. Future research directions are proposed to address remaining challenges, including improving process scalability, minimizing environmental impact, and developing cost-effective integrated systems. By consolidating current knowledge and identifying innovation opportunities, this review aims to facilitate the industrial adoption of de-ashing processes, thereby promoting lignocellulosic biomass as a viable feedstock for sustainable bioeconomy development.</p>