Semantic　relation　plays　an　important　role　in　knowledge　acquisition　research.　This　paper　proposes　a　method　of　semantic　relation　acquisition　and　automatic　synthesis　based　on　Wikipedia.　First　of　all,　we　obtain　the　three　kinds　of　basic　semantic　relations　from　Wikipedia　and　extend　the　semantic　of　concept　aiming　at　the　problem　of　semantic　fuzziness　in　the　semantic　relation.　Then,　an　automatic　synthesis　method　of　semantic　relations　is　proposed　based　on　semantic　extension.　From　the　experimental　results,　this　method　can　effectively　extend　semantic　relation　knowledge　base　through　the　reasoning　of　semantic　relations.