Abstract: The South China Sea is one of the largest marginal seas in the world.Tectonically,it lies both in the Pacific tectonic domain and Tethyan tectonic domain sandwiched between the Indian plate,Eurasian plate and Pacific plate.The collision between the Indian plate and Eurasian plate resulted in the creeping of the mantle material from the Indosinian block and South China block towards the southeast,and thus gave rise to the seafloor spreading in the South China Sea.The evolution of the Tethys and Neo-Tethys shows that the South China Sea is not a residual sea of the Tethys.Instead,it represents the reactivation of the Neo-Tethys in the South China Sea caused by the collision between the Indian plate and Eurasian plate during the closure of the Neo-Tethys.