With　the　self-compacting　concrete　as　new　concrete,　the　restrained　shrinkage　experiment　of　new　and　old　concrete　is　conducted　in　order　to　study　the　shrinkage　laws　of　repairing　concrete　restrained　by　old　concrete.　The　influence　of　concrete　strength　and　disposed　interface　is　researched　and　the　free　shrinkage　specimens　are　also　made　for　comparison.　Based　on　the　test　results,　the　shrinkage　stress　of　new　concrete　is　got　of　analysis.　The　calculating　formulae　of　restrained　shrinkage　of　new　and　old　concrete　are　put　forward　by　hyperbola　function　in　this　paper.　It　can　be　taken　as　reference　to　the　design　of　the　strengthened　concrete　structure.