The clay mineral from the sandstone reservoir with hypabyssal intrusives is analyzed by X-diffraction. Three kinds of clay mineral assemblages are recognized at Xifeng well. They are illite-smectite mixed-layer + chilkinite + chloritoid ± kaolinite ± chloritoid-smectite mixed-layer assemblage, chilkinite+chloritoid±chloritoid-smectite mixed-layer assemblage and chloritoid-smectite mixed-layer + kaolinite + chilkinite + chloritoid assemblage. The average content of chilkinite in the surrounding rocks on hanging wall decreases with the increase of the distance beyond the diabase-prophyrite. The average contents of illite-smectite mixed-layer, kaolinite and chloritoid increase with the increase of the distance. The average contents of chilkinite, kaolinite and chloritoid in the surrounding rocks on bottom wall increase with the increase of the distance. But the average contents of illite-smectite mixed-layer decreases with the increase of the distance. With the increase of the illite, the porosity and thickness of the surrounding rocks increases, while the permeability of the surrounding rocks decrease.