The present invention provides preparation methods of (+)-syringaresinol and (+)-epi-syringaresinol. The present invention also provides anti-oxidant composition including (+)-syringaresinol and/or (+)-epi-syringaresinol.本發明提供以(+)-syringaresinol及(+)-epi-syringaresinol等化合物發揮抗氧化功效之方法、該等化合物之製法、含(+)-syringaresinol及/或(+)-epi-syringaresinol之抗氧化組成物以及該抗氧化組成物之製法。