Fractal geometry provides an approach to quantitative description of complex, highly irregular systems. A review of researches in these aspects was presented here. A number of essential processes in soil are strongly influenced by microenvironment, such as:soil humic colloids form aggregates different in fractal characteristics in different microenvironments; the same micro-organisms may have structures different in fractal characteristics; and soil organic-inorganic colloids make up different aggregates, thus forming different soil structures that lead to difference in soil fertility in different microenvironments. Openness of soil structure defines pore, moisture and air distribution that are habitats of soil microorganisms. So, to understand how soil structure controls spatial distribution of microorganisms is a topic worth studying in the future.