【Objective】An aggregate is the basic unit of soil structure, and its protection of organic carbon is an important mechanism for soil carbon pool stabilization. The effects of forest types on the distribution, stability and organic carbon content of soil aggregates in Larix gmelinii forest were studied through the field investigation and laboratory analysis. 【Method】In the Larix gmelinii virgin forest in Greater Khingan Mountains in Inner Mongolia, 28 plots of 30 m× 30 m were set up according to different forest types (grass-Larix gmelinii, Ledum palustre-Larix gmelinii, and Rhododendron simsii-Larix gmelinii). The soil physicochemical indexes, soil aggregate content and organic carbon content of different particle sizes were determined by stratified samplings at 0-10 cm, ≥10-20 cm, ≥20-40 cm and ≥40-60 cm below the ground. Based on One-way ANOVA, the correlation analysis and stepwise regression analysis, the differences of soil aggregate characteristic values among different forest types and the effects of soil physicochemical indexes on distribution, stability and organic carbon of soil aggregates were analyzed, and the dominant factors that had significant influences on soil aggregates of different forest types were selected. 【Result】①The soil aggregate content in Larix gmelinii forest was the highest in particle sizes ≥0.250-2.000 mm and the content in the surface layer (0-10 cm) was significantly higher than that in the other layers. The macroaggregate content followed the order: Rhododendron simsii-Larix gmelinii > grass-Larix gmelinii > Ledum palustre-Larix gmelinii, and the forest type had a significant impact on the aggregate content of each particle size in the soil layer below 20 cm. ②The soil aggregate stability in the surface layer (≥0-10 cm) of Larix gmelinii forest was higher than that of the other layers with no significant difference among different forest types. The significant differences among different forest types mainly occurred in the layer of ≥40-60 cm, and the soil aggregate stability of Rhododendron simsii-Larix gmelinii forest was better than the other two forest types. ③ The organic carbon content of different particle sizes soil aggregates in different forest types was in the following order: (≥0.250-2.000 mm) aggregates, (<0.053 mm) aggregates, and (≥0.053-0.250 mm) aggregates. The organic carbon content of soil aggregates in the Ledum palustre-Larix gmelinii forest was the highest; the organic carbon content of soil aggregates in different forest types decreased as the soil layer depth increased, and its decline rate decreased as the particle size decreased and had obvious surface aggregation characteristics. ④The soil total organic carbon was the common dominant factor of ≥0.250-2.000 mm and <0.053 mm aggregates of the three forest types, while the dominant factors of ≥0.053-0.250 mm aggregates were significantly different across the forest types. 【Conclusion】The soil aggregates and their organic carbon contents of Larix gmelinii forest were mainly macroaggregates, and the forest type had a certain effect on the particle size distribution and stability of soil aggregates. The content of ≥0.250-2.000 mm aggregates in Rhododendron simsii-Larix gmelinii forest was the highest, and the content of <0.250 mm aggregates and the organic carbon content of soil aggregates in different particle sizes were the highest in the Ledum palustre-Larix gmelinii forest. The soil physicochemical indexes had influences on the formation and stability of soil aggregates, and the dominant factors of soil aggregates in different forest types were different. The organic matter was the main binding agent of ≥0.250-2.000 mm aggregates, while metal oxides were in favor of <0.250 mm aggregate formation. Acid soil with high soil moisture and nutrient levels are conducive to the formation of soil macroaggregates and the stability of soil structure in Larix gmelinii forest.