4,5-bis(2-bromo-4,5-dihydroxy-benzyl)-1,2-benzenediol Ⅵ was synthesized from veratraldehyde Ⅰ, by employing bromination, reduction, Friedel-Crafts alkylation and demethylation with an overall yield of 53.5%. The structure of compound Ⅵ was elucidated by spectrum techniques including 1H-NMR,13C-NMR and HREIMS. Inhibitory activities of compound Ⅵ and 4,5-bis(2-Bromo-4,5-dimethoxy-benzyl)-1,2-dimethoxybenzene Ⅴ against protein tyrosine phosphatase 1B (PTP1B) were tested by colorimetric assay. Inhibition rates of compound Ⅴ and Ⅵ against PTP1B were 25.08% and 79.48% at 20 mg•L-1, respectively, which indicated that compound Ⅵ was an potential therapeutic agent for treatment of type 2 diabetes mellitus.