In order to research the effect of forest types on the distribution pattern of soil water stable aggregate, its stability, the organic carbon component and their relationships, the distribution pattern of soil water stable aggregate, the average aggregate diameter, percentage of aggregate disruption, macroaggregate proportion and the content of organic carbon component were determined in the Eucalyptus grandi plantation, Cunninghamia Lanceolata plantation and Pinus massoniana secondary forest in Southwest Edge of Sichuan Basin, the results showed that: (1) The soil water stable aggregates in the three forests were mainly macroaggregates (> 0.25 mm). The water stability of aggregate distribution pattern was different in the three forests, the water stable aggregates of > 5, 0.5~0.25 mm in 0—20 cm soil layer, and < 0.25 mm of 20—40 cm soil layer were dominant for Eucalyptus grandi plantation, and Cunninghamia Lanceolata plantation was focused by > 5, 0.5~0.25 mm in 0—20 cm soil layer, and 1~0.5, 0.5~0.25 mm in 20—40 cm soil layer, and ≤ 0.25 mm in 0—20 cm soil layer, and >5 mm in 20—40 cm soil layer for Pinus massoniana secondary forest. The difference of soil aggregate stability was significant for different forest types in 20—40 cm soil layer, the MWD, R_0.25, PAD of Pinus massoniana secondary forest were highest. According to the Bissonnais and international soil aggregate stability classification standard, the soil aggregates could not reach the stable level (0.4 ≤ MWD < 0.8) for the three forests. (2) The content of HUC in the Pinus massoniana secondary forest was significantly higher than Eucalyptus grandi plantation, and the soil humification degree of Pinus massoniana secondary forest was the highest in 0—20 cm soil layer, while Cunninghamia Lanceolata plantation was the highest in 20—40 cm. (3) The relationships between aggregate stability and organic carbon components in three forests was different, and a significant correlation was found among MWD, SOC, FAC, and HUC. Soil organic carbon could promote soil agglomeration process and its stability, and FAC, FAC and HUC played the significant roles. In short, the soil aggregate stability, organic carbon contents and their relationships in the Eucalyptus grandi plantation, Cunninghamia Lanceolata plantation and Pinus massoniana secondary forest were significant differences, the influencing mechanisms were different. These results could provide theoretical basis for the accurate evaluation of the ecosystem function of different forest types in this region.