The invention discloses new intermediate compounds 6 and 7 of bempedoic acid, and also discloses a synthetic method of bempedoic acid. The method shortens the route steps, improves the yield, lowers the process cost, improves the structure of the bempedoic acid intermediate, enhances the crystallinity of the intermediate compounds, and is beneficial to enhancing the purity of the final product, and suitable for enlarged production. The structural formulas of the compound 6 and the compound 7 are shown in the specification, wherein -N(R2)2 represents N,N-dimethylamino, cyclohexylamino, morpholinyl or amino; and M is an inorganic base or organic alkali, and comprises sodium, potassium, calcium, cyclohexanediamine or morpholine.