Two groups of extensional structures, the N-S-trending and the E-W-trending extension structure, developed since Late Cenozoic in central Tibetan Plateau. According to remote sensing image analysis and field work in Duoma area of the South Qiangtang Basin, geomorphology is characterized by the linear distribution of fault facets, fault scarp, sag pond, thermal spring and travertine, which indicates the extension characteristics of those structures. The N-S-trending extension structures cut the ridge, Mesozoic strata and the E-W-trending extension structures with offset ranging from tens to thousands of meters. The N-S-trending strike fault spreads northward as horsetail structure from two main faults in the south and gradually disappears in the south of the central uplift belt in the Qiangtang terrane. The W-E-trending extension structure is developed in the north segments of the N-S-trending strike fault. Both fault scale and fault activity indicate that the N-S-trending extension structure is the domination tectonic unit in this area. The east-west fault is still active in Holocene according to the Optically Stimulated Luminescence（OSL）ages. The intersecting relationship between the two groups of extensional structures indicates that the E-W-trending extensional structure is the associated structure or transitional structure of the N-S-trending extensional structure. The development of the extensional structures in the two groups indicates that the central Tibet Plateau is in the state of extension collapse.