Abstract: Abstract: Soil bunds play a key role in controlling soil erosion on sloping farmlands, however, the performance and mechanism of purple soil bunds against water erosion is little reported. The objective of the present study was to analyze the soil shear strength features of purple soil bunds under different soil water content scenarios. Samples were selected from 3 types of purple soil bunds in Zhongxian County in the Three Gorges area. An unconsolidated-undrained (UU) triaxial compression test was carried out to study the soil shear strength in terms of the cohesion, internal friction angle and principal stress difference. Considering the actual water content in soil bunds and other soil physical properties, we set 6 levels of water content (from 6% to 31% with an interval of 5%) to prepare soil specimens for the test. The results showed that: 1) Within the testing water content from 6% to 31%, the soil cohesion had significant differences among different water content (P<0.05). It was increasing and then decreasing with the increment of the water content, which could be fitted by a quadratic curve. The maximum of the soil cohesion 85.52 kPa for purple bund soil occurred at the soil mass fraction of water content of 11%. When the mass fraction of water content reached 26%, the decreasing rate of soil cohesion was faster, resulting in a soil shear strength attenuation; 2) The soil water content had significant effects on the internal friction angle of bund soil (P<0.05). It decreased from 33.19° to 1.36° with the increasing soil water content, showing a first-order exponential decay. However, it decreased slowly at a high water content of 26%; 3) Significant differences (P<0.05) occurred in the soil limit principal stress difference of the purple soil bund under different soil water content. It changed obviously with the varying soil water contents and confining pressures. Under the same confining pressure, the limit soil principal stress difference decreased rapidly with increasing soil water content, indicating the reduction of soil shear strength. Under the same water content, the limit principal stress difference increased with the increment of the confining pressure. It increased relatively fast at low water contents, while slowly at high water contents. When the mass fraction of water content was 11%-25%, the soil shear strength was relatively larger than the other water content conditions. While the soil shear strength tended to be a minimum when the mass fraction of water content was about 26%; 4) The stress-strain curves of purple soil bunds affected by different water content could be categorized into 3 types, that is, softening type, hardening type and weak hardening type. In the condition of small confining pressure and low water content, a maximum appeared in the stress-strain curve, showing a softening type. When the water content and confining pressure increased, the stress-strain curve gradually changed to a hardening type. However, the stress-strain curves gradually transformed into a weak hardening type under a condition of high water content. The results can provide support for bund construction in ecological projects, for example, high standard basic farmland construction, in the Three Gorges Reservoir area.