The permeability of rock is apparently dependent on the direction or anisotropic, which is resulted from the rock-forming geological processes. At present, theoretical and experimental studies on directional permeability properties of sandstone remain insufficient, and there is lack of quantitative assessment on the anisotropy of permeability. The transient tests are performed on sandstone from CCUS by orthogonally sampling cores. Experiential results indicate that there exists a power function relation between the permeability and the confining pressure. However, as the confining pressure is increased up to 20 MPa, the difference of permeability inorthogonal direction declines gradually, which shows a convert of permeability from anisotropy to isotropy. The pressure sensitivity of the permeability in the vertical coring samples is generally lower than that in the horizontal ones. Furthermore, a theoretical model is deduced in the Cartesian coordinate for the anisotropic permeability, which can be used to explain the vector properties of rock permeability. The parameter of anisotropy ?k is also proposed on the basis of the standard deviation and then is employed to normalize the heterogeneity of permeability in different reservoir sandstones. It shows that the proposed method is quantitative to describe variations of anisotropy in the seepage field system.