[Objective] The soil aggregate stability of different species of Pinus yunnanensis in the karst mountain area of Eastern Yunnan Province was studied to provide a basis for soil cultivation, quality improvement, and soil-water conservation of karst fragile habitats.[Methods] Based on the field survey and laboratory analysis, five types of vegetation, namely P. yunnanensis pure forest, P. yunnanensis artificial mixed forest, P. yunnanensis natural mixed forest, shrub, and primeval forest, in the karst mountains of Eastern Yunnan Province were studied in terms of their characteristics of water-stable aggregate and organic carbon distribution in aggregate, which revealed the differences in the soil aggregate stability of different species of P. yunnanensis.[Results] ① The mass fraction of particle size <0.25 mm (5.77%~9.39%) of P. yunnanensis pure forest, artificial mixed forest, and natural mixed forest was significantly lower than that of shrub (20.92%) and primeval forest (27.47%) (p<0.05). The mass fraction of particle size >5 mm and 2~5 mm of artificial mixed forest and natural mixed forest was higher than that of pure forest. ② The proportion order of water-stable aggregate >0.25 mm (R_0.25) after wet sieving treatment was P. yunnanensis artificial mixed forest > P. yunnanensis natural mixed forest > P. yunnanensis pure forest > shrub > primeval forest. The mean weight diameter order was P. yunnanensis artificial mixed forest > P. yunnanensis natural mixed forest > primeval forest > shrub > P. yunnanensis pure forest. The geometric mean diameter order was P. yunnanensis artificial mixed forest > P. yunnanensis natural mixed forest > primeval forest > P. yunnanensis pure forest > shrub. The fractal dimension order was primeval forest > shrub > P. yunnanensis pure forest > P. yunnanensis natural mixed forest > P. yunnanensis artificial mixed forest. ③ The contribution rate of large aggregates (>0.25 mm) of P. yunnanensis pure forest, P. yunnanensis artificial mixed forest, and P. yunnanensis natural mixed forest to soil organic carbon was higher than that of small aggregates (<0.25 mm), and the content of organic carbon in soil aggregates with particle sizes of 5, 2~5, and <0.25 mm was significantly lower than that of shrub and primeval forest (p<0.05).[Conclusion] P. yunnanensis artificial mixed forest was observed to have the maximum soil aggregate stability, and its nutrient accumulation and carbon sequestration were lower than those of shrub and primeval forest but higher than those of pure forest. When the P. yunnanensis artificial mixed forest was planted as the main vegetation type for soil and water conservation in this region, it was necessary to avoid human interference for the purpose of improvement of soil nutrients.