According to field survey, drilling cores, thin slice and logging data, based on the tectonic stress field analysis, this paper analyzed the types and origin of fractures of the Xujiahe Formation in the Sichuan Basin. The result shows that under the action of the NW horizontal compressive stress in the late stage of Indo-China movement, the approximate NS and NW trending “X” plane conjugate shear fractures and a few NE trending tectonic associated fractures were formed. Due to the influences of the strong stratum heterogeneity, the development degree of NW trending fractures is higher. During the period of late-mid-Himalayan movement, under the action of the EW horizontal compressive stress，the former fractures were reformed that the NW-SE trending fractures were enhanced and the NS trending fractures developed into thrust fault with strike-slip characteristics. And in the NE local stress field，approximate EW trending fractures developed in the northeastern study area. Under the action of nowadays NW trending tectonic stress field, the NW trending fractures are more open, and the approximate NS and NE trending fractures are closed. The distribution of regional fractures superposed associated fractures is closely related to local structures. The area where kinds of fractures developed is favorable for fracture development, so the development area of NW and approximate EW trending effective fractures will be the key area for oil-gas exploration in Dayi area.