Fractal geometry is a method of discovering the rules such as self-similarity of irregular curves

the self-inverse of irregular figures

the self-squaring of fractal translations

the self-affine of fractal groups and so on. If it applies on the research jobs of micro-structural fractal features

some key-techniques of soil microstructure mechanic would soon be solved. To use the fractal geometry in micro-analysis of saturation soft soil

the most important thing is to get microstructure fractal features parameters such as the fractal dimension of grains

the fractal dimension of holes. With the liquid nitrogen refrigeration sample-made technique

the scan electronic microscope technique （SEM） and the image-processing-analysis and computer-vision technique，46 group samples’ microstructure fractal features parameters of saturation soft soil which withdraw from Guangdong Scientific Center are extracted. By adopting variable gradually linearization regress analyses

the relationship between the fractal features and the porosity are discussed.