Abstract: A borehole wall spin-shearing device includes a load applying assembly, a soil shearing assembly, and a data acquisition assembly, where the load applying assembly is configured to apply a vertical load and an axial rotational load to the soil shearing assembly; the soil shearing assembly includes a plurality of shear plates; the plurality of shear plates are configured to penetrate into undisturbed soil after being ejected due to the vertical load and then shear the undisturbed soil due to the axial rotational load; and the data acquisition assembly is configured to acquire torque values of the plurality of shear plates during a process of shearing the undisturbed soil. The borehole wall spin-shearing device can directly conduct an in-situ borehole shear test in an exploration borehole with a conventional diameter in China, reducing the cost of drilling. The borehole wall spin-shearing device achieves a high degree of automation throughout the test.