Abstract: According to the data of physical exploration,drilling,landforms etc.,we proved the existence of Wanghu Beitian fault and Guojiabu Nangou fault as well as their activity.Through discussion in distribution of faults and its activity feature,seismic distribution,underground water,landforms,crustal deformation etc.,it is confirmed that Yuci ground fissure was cause by fault activities,which is one kind of tectonic cause.Seismicity and overextraction of underground water intensified the development of the fissure.