[Objective] The effects of different plantation types on understory vegetation community structure， species diversity， and soil physicochemical properties in Pisha sandstone area were analyzed， in orderto select suitable tree species for constructing soil and water conservation forests and provide a scientific basis for vegetation restoration and species diversity conservation in Pisha sandstone area. [Methods] Four typical plantation types （Caragana korshinskii， Prunus sibirica， Hippophae rhamnoides and Pinus tabuliformis forest） in Baojiagou watershed of Nuanshui Township， Jungar Banner， Ordos City， Inner Mongolia Autonomous Region， were selected as the research objects， with natural grassland （CK） as the control. Through field surveys， sampling， and laboratory experiments， the relationships among understory herbaceous plant community composition， species diversity， and soil physicochemical properties the natural grassland and the four typical plantations were investigated. [Results] ① The understory herbaceous vegetation in the study area comprised 23 species from 18 genera and 10 families. The C. korshinskii forest had the highest number of understory herbaceous species， with a total of 22. The understory herbaceous plants in the four plantations were mainly composed of species from the Asteraceae， Gramineae， and Fabaceae families. ② The coverage， biomass， Margalef richness index， and Shannon-Wiener diversity index of the understory herbaceous layer under the C. korshinskii forest were significantly higher than those under other vegetation types （p<0.01）. ③ The soil moisture content， soil organic matter， and total nitrogen content under the C. korshinskii forest were significantly higher than those under other vegetation types （p<0.01）. Soil organic matter and total nitrogen exhibited a surface aggregation effect. ④ Soil organic matter and saturated hydraulic conductivity were the dominant factors affecting the species diversity of the understory herbaceous layer in the plantations， while topography was a secondary factor. [Conclusion] C. korshinskii is the preferred tree species for constructing soil and water conservation forests in the Pisha sandstone area of Jungar Banner. It plays a dual role in maintaining species diversity and improving soil quality.