Abstract: Stability and phisical properties of the soil aggregates from three rubber-based(Hevea brasiliensis) agroforestry ecosystems with different interplants(Camellia sinensis,Theobroma cacao,Flemingia macrophylla),and a monoculturerubber forest were studied in Xishuangbanna,Southwest China.The results showed that the physical properties of rubber-based(Hevea brasiliensis) agroforestry ecosystems presented lower soil bulk density,and higher soil porosity in comparison with the monoculture ecosystem.Bulk density and porosity in rubber agroforestry ecosystems were both significantly related to the contents of water-stable aggregates (>2mm and >0.25mm) and stability indices of the aggregates;The contents of water-stable aggregates(>2mm and >0.25mm)in Hevea brasiliensis-Theobroma cacao and Hevea brasiliensis-Flemingia macrophylla ecosystem (except the Hevea brasiliensis-Camellia sinensis agroforestry ecosystem) were much more than that of the monoculture ecosystem,and decreased by the soil depth;Compared to the monoculture ecosystem,MWD and GMD in rubber-based agroforestry ecosystems were both significantly increased,while dimension value (D) was significantly decreased.The results proved that soil aggregates and soil quality were getting more stable and significantly improved after the construction of rubber-based agroforestry ecosystems.Stepwise regression and variance analysis indicated that mean weight diameter (MWD) can be considered as a good index for the soil structure stability in this area.