The swell soil landslide in Xianshanya area, Xiangfan, Hubei Province, is disastrous on the traffic. Plenty of funds have been invested to solve the problem but have not produced any good result. This is perhaps mainly due to the lack of understanding of the swell soil. Based on some characters of the landslide, the X-ray diffraction (XRD) and X-ray fluorescent (XRF) spectrum and scan electron microscope (SEM) are used to study the physical properties and the microstructure of the swell soil of landslide. Then, the effect of some characters in the formation and evolvement of the swell soil landslide is discussed with more illustration of the landslide formation mechanism. Meanwhile, some important rules of the swell soil of landslide are summed up combined with this area's geological conditions. This may serve as some references for the prevention in the swell soil area.