Abstract: Saturated clays with different water content and different pore water natures have different compressive deformation mechanism. Loose and high water content clayey soils saturated with gravity water, fit Terzaghi consolidation theory. Dense and low water content clayey soils contained absorbed bound water only don’t fit it. This paper presents test results of variation of pore water pressure and volume strain of a clay sample saturated with gravity water during a high pressure triaxial compression test. The aforementioned viewpoint has been verified preliminary.