There is a special kind of flower structures in the Qingdong sag, termed as composite flower structure, which developed upon the large NW-NWW trending basement faults. Based on analysis of 3D seismic profiles and surface structures, it is found that faults in the belts present an en-echelon or parallel arrangement horizontally, and these special flower-like structures are composed of a major basement fault that radiates upward, and many subsidiary faults on vertical profiles. According to the fault characteristics and stress field evolution in this area, it is proposed that the composite flower-like structures are caused by structural superimposition of earlier transtension faulting（oblique extension）along the NW to NWW-striking basement faults under a N-S extension and later transpression faulting due to the inversion at the end of Paleogene. Evolution of the composite flower structures experienced formation of the negative flower-like structure during the Paleogene extension and antiform structure overprinting during the inversion period at the end of Paleogene.