The invention relates to a chemical total synthesis method for a PTP1B inhibitor and the application in drugs for treating type 2 diabetes mellitus. The chemical structural formula of the PTP1B inhibitor is as follows, wherein each carbon at 2, 2', 3, 3', and 6 position of a phenyl ring is connected with a group of bromine atom; each carbon at 4, 4', 5, 5' position is connected with a hydroxyl; the chemical name in English is (2',3'-dibromo-4',5'-dihydroxy-phenyl)-(2,3,6-tribromo-4,5-dihydroxy-phenyl)-methanone. The compound enhances the sensitivity of insulin receptors by inhibiting the activity of protein tyrosine phosphatase 1B, and has good therapeutic effects on insulin resistant type 2 diabetes mellitus.