Using the analytical means such as ordinary thin slice, cast thin slice, scanning electron microscope and X_diffraction, the authors conducted researches on the characteristics of petrology, diagenesis and pore evolution of the 2nd Member sandstone reservoirs of Xujiahe Formation in Hechuan area, and the result indicates that the sandstone reservoirs are mainly composed of feldspar lithic sandstone and lithic sandstone, which have mainly experienced compaction, cementation, dissolution and metasomatism, with the diagenetic phase reaching the middle diagenetic stage B. Primary pores decreased rapidly due to strong compaction during the early diagenentic stage A～B, and primary pores were reduced continuously due to the compaction and siliceous cementation, together with the increase of induced pores resulting from the dissolution of feldspars and the cutting of grains rich in feldspar during the middle diagenetic stage A. In addition, the metasomatism_filling of iron_bearing calcite and ankerite caused the tightness of the reservoir during the middle diagenetic stage B. The compaction and cementation seem to be the main diagenetic types which destroyed the primary pores. The dissolution was the main diagenetic action to form the induced pores. Controlled by diagenesis and diagenetic phase, there exist many types of reservoir space in the 2nd Member of Xujiahe Formation in Hechuan area: intragranular dissolving pores, intergranular dissolving pores and remnant intergranular pores are well developed, and the induced pores growing belt abnormally appears in the 2nd Member of Xujiahe Formation in Hechuan area, resulting from the corrosion of feldspars and the cutting of grains rich in feldspar.