Abstract: Based on data of gravity survey, seismic exploration, aerial magnetical survey and surface geology, the central fault belt was identified in the Qaidam Basin. The basin was divided into two differnt parts by the fault and indicated existence of old crystaline continental kernel pre-Wutai movement. In accordance with geochemical data of intermediatoacid intrusives, a conclusion can be drawn that there was an old altyn Ocean, which expanded the scope of the paleo-Qing-Qi-Kun Ocean. The Altyn Ocean was closed during the Altgn Movement and the arc became pre-Cambrian folded accreted belts.