The invention relates to the field of soil mass engineering, and in particular relates to a multidimension permeability coefficient measuring instrument and measuring method. The measuring instrument comprises a shell, a square cutting ring, a water insulation tank, a left cuboid glass tube and a back cuboid glass tube, wherein the square cutting ring is supported in the middle part of the shell and provided with a dismountable bottom at the lower side; the water insulation tank is supported in the middle part of the shell and covered above, below and around the square cutting ring; the left cuboid glass tube is supported at the left side of the water insulation tank, shaped like a right-angle U and provided with a bottom; and the back cuboid glass tube is supported at the back side of the water insulation tank and provided with a bottom. The measuring instrument and measuring method adopt water absorption sponge for water absorption and calculate flow through the change amount of the mass of the water absorption sponge, and a computer performs calculation according to the Darcy's law or other formulae and then outputs. For measurement of the coefficient of percolation in the horizontal direction, percolated water can be absorbed in time by using the sponge for water absorption, thereby preventing the percolated water from leaving along the wall of a soil sample, generating reverse percolation and the like, and avoiding influences on measuring results.