Abstract: This study systematically investigated the chemical composition of heartwood and sapwood from 5- and 7-year-old Acacia melanoxylon in Guangxi Province, including cellulose, hemicellulose, lignin, extractives, ash content, and pH. Results indicated that sapwood had significantly higher holocellulose content (P<0.05), while heartwood contained more lignin and extractives (P<0.05), with lignin content increasing with tree age (P<0.05). Significant variations were observed in both radial distribution and tree age (P<0.05). Correlation analysis revealed negative relationships between carbohydrates and lignin/extractives (P<0.05). In summary, the sapwood of A. melanoxylon was well-suited as a high-quality raw material for pulp and papermaking as well as biorefining. In contrast, due to its high extractive content, the heartwood required optimization of bonding processes when used in the manufacturing of engineered wood products and similar processing applications.The findings provide a theoretical basis for the targeted processing and high-value utilization of A. melanoxylon.