The micro pore structure of isotropic consolidated clay was studied by using a scanning electron microscope (SEM). A digital imaging technique was applied to analyze the evolution of size, number of pores and their distributions in the process of isotropic consolidation according to the SEM images. Based on the fractal concepts of Koch curve and Sierpinski carpet, the Koch fractal dimension Dk and the Sierpinski fractal dimension Ds of soil pores are obtained from the measured data. The variations of both Dk and Ds following the change of micro pore parameters and mechanical properties of clay are investigated. The results show that the porosity and pore size decreases as the consolidation pressure increases, and the range of pore size becomes narrower. Dk reflects the degree of irregularity of the pore-solid interface in soil, and the larger the Dk the more irregular the soil pore profile. The distribution of Dk was found in agreement with a total normal distribution in soil pore. The magnitude of Ds reflects the variation of porosity of clay under isotropic consolidation. Large fractal corresponds to large consolidation pressure and small porosity. Ds displays a significant linear regression relationship with porosity, consolidation pressure, consolidation deformation of clay and an exponential growth relationship with permeability coefficient of clay. Both Dk and Ds is sensitive to isotropic consolidation of soil and they may be cited as useful indicators for soil consolidation.