[Objective] The dynamic characteristics of soil moisture of five different vegetation types were studied to provide a theoretical basis for optimizing plantation mode.[Methods] Five typical vegetation types from the semi-arid loess hilly region of Dingxi City, Gansu Province, were selected. The soil moisture content of the soil layer from 0 to 200 cm in depth was observed in 2017 and 2018 using a soil moisture tachometer. The characteristics and stability of soil moisture of different vegetation types were analyzed.[Results] ① The soil moisture content of different vegetation types was:mixed forest of Armeniaca sibirica and Platycladus orientalis (11.24%) > Medicago sativa grassland (10.97%) > natural grassland (10.66%) > returning farmland (9.99%) > Caragana korshinskii forest (9.55%). ② According to the orderly clustering method, the 0-200 cm soil layer of the five vegetation types could be divided into three sublayers:dynamic change layer (0-40 cm), utilization layer (40-100 cm), and weak utilization layer (100-200 cm). In the dynamic change layer (0-40 cm), the soil moisture content was the highest in the natural grassland (14.23%) and lowest in the C. korshinskii forest (11.04%); In the utilization layer (40-100 cm), the soil water content was the highest in the M. sativa grassland (12.16%) and lowest in the C. korshinskii forest (9.15%); In the weak utilization layer (100-200 cm), the soil water content was the highest in the natural grassland (10.81%) and lowest in the returning farmland (8.61%). ③ The layer stability of soil moisture (coefficient of variation) in the different vegetation types was:returning farmland (19.9%) < mixed forest of A. sibirica and P. orientalis (21.3%) < natural grassland (21.9%) < M. sativa grassland (22.6%) < C. korshinskii forest (23.6%). ④ The temporal stability of soil moisture (coefficient of variation) in the different vegetation types was:natural grassland (25%) < returning farmland (25.2%) < mixed forest of A. sibirica and P. orientalis (26.5%) < C. korshinskii forest (27.1%) < M. sativa grassland (31.9%).[Conclusion] In the semi-arid loess hilly region, the soil moisture content was the lowest in the C. korshinskii forest. This vegetation type also had the most unstable layer and temporal stability. The soil moisture content in mixed forest of A. sibirica and P. orientalis was higher and more stable than other vegetation types.