The Yagan metamorphic core complex(MCC)is composed of low plate metamorphic crystalline core, detachment fault zone and upper plate. The core can be subdivided into two tectonic slices: the high-grade metamorphic slice in the lower and the low-grade metamorphic slice in the upper. The former consists of amphibolite facies banded gneisses and marble gneisses, and the later of quartz schists. Between the both occurs a granitic mylonite zone. The major detachment fault zone is composed of mylonitic zone, chloritized zone, breccias pseudotachylite zone, fault surface and cataclasitic zone. The upper plate of the MCC consists of anchimetamorphic Permian, Jurassic and Cretaceous as well as exotic blocks of the Proterozoic dolomitic marbles. In a whole, the MCC can be divided, structurally, into three layers separated by two detachment zones, instead of a simple two plate mode. All these units arrange in outward(ascending)order, keeping the original relationship. Additionally, the deformation is characterized by foliation and lineation, instead of folds. Such a feature of stratum framework in extensional regime means structural nappies of extension and elevation of tectonic slices by several detachment zones and shows a characteristics of poly-layer extensional tectonic systems. It provides an example that a large scale extensional system, including more than one detachment zones, consists of several tectonic slices, stacking up regularly, as a series of thrust slabs, which may have some rheological information on continental crust section.