This study employed a one-step synthesis method to prepare Beta zeolites (BZs) with various SiO2/Al2O3 ratios and applied them as catalysts in the process of producing bio-oil from Kraft lignin (KL). The research investigated the changes in acidity and pore size of BZs under different SiO2/Al2O3 ratios and their impact on the catalytic pyrolysis products of KL. Characterization and a series of physicochemical analyses of BZ with different SiO2/Al2O3 ratios as well as catalytic pyrolysis products were carried out. The Pearson correlation coefficient was also used to correlate BZ SiO2/Al2O3 ratios and the acidity/pore size of BZ as well as the distribution of the products and the deoxygenation effect. The results indicate that BZs with different SiO2/Al2O3 ratios can effectively catalyze the upgrading of KL during pyrolysis. BZ with SiO2/Al2O3 ratios of 45 exhibited stronger acidity, a more prominent layered porous structure, and a more orderly distribution of mesopores. It showed the best catalytic upgrading effect on KL, achieving a product yield of 58.4 %. More prominently, the oxygen content is reduced to 14.19 % and the deoxygenation extent of the heavy oil reached 37.1 %.