The M_L4.4 earthquake in Lincheng occurred on September 4,2017,which was the only M_L4 or greater earthquake in Xingtai region since 2003. The aftershocks were distributed along a belt,which reveals an unknown blind fault(named as the Qijiazhuang-Dongshuangjing fault after the sites it passed by). In order to study the geometry and slip property of this blind fault,we firstly relocated the earthquake sequence by using the Hebei digital seismic network bulletin and obtained the strike,dip and their standard deviation of the fault plane parameters by applying the accurate positioning earthquakes. Secondly,we collected the focal mechanisms of the historical earthquakes near the epicenter,and inverted the regional stress field using the grid search method,and determined the sliding property of the Qijiazhuang-Dongshuangjing fault. The results showed that the seismogenic fault of the Lincheng M_L4.4 earthquake was a blind fault in East-West direction. The strike,dip and rake is 92°,85ånd -12°,respectively,with the standard deviation of rake about 8°. The fault is in south dip direction,with steep and left-lateral strike-slip up to depth of 10km. The relative shear stress and normal stress on the Qijiazhuang-Dongshuangjing fault was estimated as 0.650 and 0.691,respectively,based on the regional stress field. The orientation of the Qijiazhuang-Dongshuangjing fault is not the maximum shear stress fault,which suggests that the found blind fault is not generated by the contemporary tectonic stress,but is left behand the complex historical geological activity. The stress on the Qijiazhuang-Dongshuangjing fault accumulated to a certain extent and resulted the occurrence of the M_L4.4 earthquake. The finding of the Qijiazhuang-Dongshuangjing fault and its property provides a solid foundation on tectonics and seismogenic analysis in study region.