Abstract: The hydrothermal pre-hydrolysis of broadleaf acacia woods was carried out by different pre-hydrolysis strength (P factor), and through the analysis of the yield, composition, 1% NaOH extractive, benzene-alcohol extractive, elemental analysis, water absorption, alkali consumption and surface morphology of pre-hydrolyzed wood chips, the influence of pre-hydrolysis strength on the content of the extract components and solvent absorption properties were discussed. The results showed that with the increase of the P factor, the yield of wood chips and the content of holocellulose, pentosan and lignin after pre-hydrolysis all showed a decreasing trend. However, the content of sodium hydroxide extractive and benzene-alcohol extractive first increased and then decreased. When P factor was 0-800, the content of 1%NaOH extractive and benzene-alcohol extractive increased from 12.04% and 1.74% to 25.98% and 12.11%, respectively; when P factor was increased from 800 to 1 000, the content decreased from 25.98% and 12.11% to 23.19% and 11.08%, respectively. The lignin content of 1% NaOH extractive increased from 7.15% (when P factor was 0) to 48.37% (when P factor was 1 000), while the lignin content of benzene-alcohol extractive increased from 16.42% (when P factor was 0) to 47.68% (when P factor was 800).According to the results of water immersion and alkali immersion experiments, as the P factor increased, at the early stage of pre-hydrolysis (P factor was 0-310), the water absorption and alkali consumption of pre-hydrolyzed wood chips both showed a increasing trend, and the absorption properties of pre-hydrolyzed wood chips improved, and then decreased.When P factor was 310, the water absorption and alkali consumption were higher, which were 1.542 3 g/g and 80.71 mg/g respectively. The surface morphology analysis results showed that with the increase of P factor, the surface of the wood chips after pre-hydrolysis became looser and more porous.