Southeast Gansu province Seismic Belt, the tectonic northeastward growth o{ the activities along and Tibetan Plateau. the central-northern portion of deformation Complicated pattern are closely the South North related to the structural geometries were controlledby both Eastern Kunlun and West-Qinling Northern Faults, and outward growth of the NE Tibet continuously contributes to the regional active deformation. In recent years, intermediate strong earthquakes occurred frequently, calling for a detailed analysis. By integrating both structural and historical seismicity studies, and combining geophysical, seismological and field investigations, we conclude that northward indenting and eastward movement along the Eastern Kunlun Fault is the main tectonic stress source, and also it provides the basic setting and mechanism to generate strong earthquakes. Left-lateral slip and its bi-flanking thrusting "flower structure' of the West- Qinling Northern Fault contributed to the frequent occurrence of intermediate-strong earthquakes along the Lintan-Tanchang fault to the south. Minxian-Zhangxian Ms6.6 earthquake on July 22, 2013 along the central eastern Lintan-Dangchang fault is a consequence of differential activity due to heterogeneous segments.