The application discloses a shear test device. The shear device comprises a test container and a rotary shear loading device; the test container is used for holding a to-be-tested sample and at least comprises a bottom plate and a side wall; the bottom plate of the test container is provided with an axial hole for placing a shear plate rotating shaft; the rotary shear loading device comprises a shear plate and a torque applying device, wherein the shear plate is installed on the axial hole of the bottom plate of the test container through the shear plate rotating shaft and can rotate around the shear plate rotating shaft; the torque applying device is used for driving the shear plate to rotate around the shear plate rotating shaft and realizing the rotating shear of the to-be-tested sample held in the test container. The shear test device and method have the advantages of realizing fixed area of a shear face, uniform stress of the shear face, and unlimited shearing displacement during the shear test process, and meeting the testing requirement of wide particle size of the test sample.