The invention provides an angular soil sampling device. The device comprises a fixing device and a soil sampling device, wherein the fixing device is a right-angular tetrahedron frame formed by welding steel angles; and the soil sampling device is positioned outside of the fixing device, and is connected with the fixing device through a cylindrical cross bar and a rotating rod with a sleeve. The invention further provides a method for operating the angular soil sampling device. The device is simple in structure and low in cost. The device is simple and convenient in sampling operation, can be used for quickly and accurately determining an inclined angle between a soil sample and the horizontal ground and the depth of the oil sample and supplying samples for testing the mechanical and hydraulic anisotropies of undisturbed soil. By adopting the device, the shear strength of five groups of soil samples with same angle and depth in a certain region are tested to obtain the average shear strength of 76.34kPa, the variance among data being 0.452 and the maximal difference values of shear strength being 0.9kPa. The angular soil sampling device can meet the requirement for accuracy of the engineering on each anisotropic test of soil.