Abstract: A direct compacting way is adopted to determine the permeability coefficient using ameliorated clay permeameter. Thus the side leakage is prevented and the experimental error is reduced. By using air to compress, the experimental period for the determination is reduced from 1-2 months to 2-3 days. The experimental data are comparable to those obtained from the normal standardized permeameter and can be used in the research of permeation velocity, transformation, absorption and exchange of poisonous substances in clay. The improved permeameter is easy to handle.