Abstract: According to the records of the formations of the paleo Tethys and from an analysis of the tectonic displacement, it is considered that the east section of the paleo Tethys is defined by the boundary which extended from what is now Qinghai Tibet to West Yunnan, then southwards to Pütog, Changning Menglian, Uttarradit and Bentong Raub, passed through Pulau Kalimantan (Kuching), Palawan, Luzon, finally reached Taiwan and Japan. The present “U”shape of the paleo Tethys suture zone was attributed to the contortion caused by the northwards impinging of the Indian plate, the spreading of the South China Sea and the westwards pushing of the Philippine Sea plate since 45 Ma. But the restored paleo Tethys suture zone extended EW strikingly from late Cretaceous to early Cenozoic. Covering an area from West Guangxi, Southeast Guangxi, West Guangdong, Central Jiangxi, Fujian to Zhejiang, the present South China area belongs to an active continental margin, which would be converted from the disintegrated northern paleo Tethys during subduction northward at first to closing finally.