To clarify the effects of different slope positions and land use types on the composition, stability, and nutrients of soil microaggregates in a karst valley area. Taking slope positions with different land use types in the karst valley area of Youyang, Chongqing as the study subjects, the composition, structure, and nutrient characteristics of soil microaggregates under different slope positions and land use types were analyzed through field surveys and laboratory experiments. The results showed that: (1) The dominant particle size fraction of soil microaggregates in the study area was 0.05–0.001 mm (47%–68%). As slope position decreased, the proportion of the 1–0.25 mm fraction decreased significantly, while that of the 0.05–0.001 mm fraction increased significantly (p<0.05). The average content of large aggregates in forest land was 12.8% and 50.6% higher than that in Sichuan pepper fields and shrub-grasslands, respectively. (2) The MWD and GMD ranged from 0.09–0.19 mm and 0.04–0.06 mm, respectively. In both Sichuan pepper fields and forest land, MWD and GMD were higher on the upper slope position than on the middle and lower slope positions; in shrub-grassland, they were higher on the middle slope position than on the upper and lower slope positions. Overall, forest land exhibited the highest soil stability. (3) Forest land had the highest TN and SOM contents (2.16 g/kg and 37.05 g/kg, respectively), while Sichuan pepper fields had the highest TP content (1.46 g/kg). TK was less affected by slope position and land use type. From the upper slope position to the lower slope position, TP content increased significantly (p<0.05); TN showed no significant variation with slope position; and SOM exhibited opposite trends along the slope position between forest land and shrub-grassland. (4) Across all slope positions, MWD and GMD were highly significantly positively correlated with large aggregates and significantly negatively correlated with the 0.05–0.001 mm fraction. On the upper slope position, both MWD and GMD were significantly positively correlated with TP. On the middle slope position, MWD was highly significantly positively correlated with TP, and GMD was highly significantly positively correlated with TN. On the lower slope position, no significant correlations were found between MWD, GMD and soil nutrients. In conclusion, slope position and land use type jointly influence the composition and stability of soil microaggregates. Forest land is conducive to maintaining a higher proportion of large aggregates and improving structural stability. In the ecological restoration of karst valley areas, forest restoration or enclosure protection should be prioritized at the upper slope position, while at the lower slope position, human disturbance should be reduced and soil and water conservation measures strengthened to mitigate soil structural degradation.