The status of soil aggregates is an important factor affecting soil fertility.In this work,the fractal model was used to study the soil aggregate structure under different stand management patterns and to inquiry the relation between fractal dimension and soil fertility.The results indicated that the higher the content of water stable aggregates and water stable big aggregates in soil,the smaller the fractal dimension of soil aggregates,and the higher the soil fertility.There were remarkable regression relationships between the fractal dimension of soil aggregates and the contents of water stable aggregates and water stable big aggregates.The fractal model could be a new tool for the research on soil fertility.