Abstract: Accurate and easy determination of anisotropy permeability of sand stone is one of key points for construction of a water-sealed cavern in the sandstone. A calculation formula of equivalent permeability coefficient for conversion from permeability tensor to scalar value was deduced in light of the spatial geometric principles based on an analysis of three-dimensional permeability tensor matrix, the calculation results of tensor matrix of permeability coefficient were modified on the basis of conventional water pressure test data. It suggests that borehole ultrasonic imaging test system should be adopted to obtain geometric factors of joints and fractures which are the input data of tensor matrix calculation, and a determination method of anisotropy permeability coefficient of sandstone was established by combination of permeability tensor matrix and conventional water pressure test results. Engineering cases have proved that this method is easy to operate and the results are accurate.