The invention discloses a permeable pavement permeability coefficient testing device and a testing method, relates to the field of permeable pavement permeability coefficient testing, in particular tothe permeable pavement permeability coefficient testing device and the testing method, and provides the permeable pavement permeability coefficient testing device which is simple in structure and convenient to process and improves test stability and the testing method . The device comprises a measuring cylinder, a transparent cylinder and a sealing ring, the transparent cylinder and the sealing ring are communicated with each other and arranged on the upper portion and the lower portion respectively, the center line of the measuring cylinder and the center line of the transparent cylinder arein the same straight line, the cylinder diameter of the measuring cylinder is smaller than the diameter of the transparent cylinder, an annular groove is formed in the top surface of the sealing ring, and the transparent cylinder is disposed in the annular groove; the invention further comprises a water permeable mechanism, and the water permeable mechanism is detachably connected in the transparent cylinder. The testing method of the permeability coefficient is very suitable for a pavement with a large permeability coefficient, especially a permeable pavement e of 'permeable brick and aperture permeability', and the testing operation is convenient.