Fractal characteristics of soil aggregate structure under Cunninghamia lanceolata and Phyllostachys edulis mixed plantations in Fujian were studied by using fractal theory. Six plots with different Cunninghamia lanceolata and Phyllostachys edulis densities in mixed plantations, and two plots of pure stands of the two species were chosen. All the plants in plots were 19-year-old. Regression models for fractal dimension (D) of aggregated structure and water stable aggregate (>0.25 mm) content, and for D and destroyed structure percentage，were established．The effect of fractal dimension of aggregates on soil properties were evaluated by elasticity and limit analyses． The results showed that the higher the content of water stable aggregates(>0．25 mm or>5．0 mm)in soil，the smaller the fractal dimension of aggregates，and thus the beaer structure and stability the soil． The regression relationships of all the model were remarkable． Fractal dimension variation of aggregate structure had a great effect on soil properties， which will provide a scientific basis for the culture of such mixed forest.