As a new type of special soil macropore types, root-soil annulus plays an important role in the process of rainfall infiltration of soil on a vegetated slope. Soils were collected in the high coverage slopes of different vegetation communities in the experimental area of Chenggong, the characteristic parameters of the macropores were obtained by using the moisture breakthrough method, then the flow characteristics of the root-soil annulus were studied combined with mathematical model of annular tubes. Results showed there was little difference between the sizes of the root-soil annulus of the woody and herbaceous vegetation communities, which were distributed in the ranges of 0.62–1.02 mm and 0.67–1.12 mm, respectively, and the annulus scales in different layers in the former vegetation community were smaller than those of the latter. The maximum values of u/u_m of root-soil annulus channels in the soils under the two vegetation communities increased with depth, however, the value was nearly the same; within the scope of the depth, the r value was in advance when u/u_m of the soil layer reached the maximum value, and the corresponding r values of all layers of woody soil were greater than those of the herb. The differences between the size of root system and the annulus were the main reasons for the formation of the above characteristics. Under the same of the number of fluid channels and Reynolds number, the average flow velocity, maximum velocity and flow contribution rate of the annular increased with depth, however, the situation of flow was opposite. In addition, the flow rate, flow and contribution rate of woody plant soil in each layer were higher than those of herb plant soil.