Immersed　tunnel　was　constructed　in　the　year　1910　at　the　first　time.　The　next　few　decades,　there　were　more　than　one　hundred　immersed　tunnels　constructed　in　the　world.　Zhoutouzui　Immersed　Tunnel　of　Guangzhou　City　is　the　seventh　underwater　tunnel　in　Chinese　Mainland.　It　is　one　concrete　tunnel　with　rectangular　cross-section　which　is　variable　because　of　the　constraint　conditions　at　overpass.　It　has　distinct　feature　in　China＇s　tunnel　design.　The　overall　design　and　technical　characteristics　of　Zhoutouzui　Immersed　Tunnel　are　described　in　detail.