The free section of prestressed anchor cable is a weak part of support. A new supporting structure named Anchor Cable and C-Shaped Tube, which can bear transverse shear force, solves the problem that rock bolt and anchor cable are prone to shear failure in the free section and also solves the contradiction between high preload and low shear bearing capacity of support materials. Double-shear tests of Anchor Cable and C-Shaped Tube with smooth joint planes were carried out. Double-shear tests were carried out on the anchor cables with the diameter of 21.6 mm and the same type of Anchor Cable and C-Shaped Tube under different preload conditions. The influence of the preload on the shear performance of supporting materials and the enhancement effect of Anchor Cable and C-Shaped Tube supporting structure on the shear performance of anchor cables were analyzed. The test results confirm that Anchor Cable and C-Shaped Tube can improve the transverse shear resistance of the supporting material and increase the axial ultimate bearing capacity of the anchor cable during the shearing process. It is found that, during the double-shear test, the fracture form of the supporting materials is tensile fracture, and when it is sheared, Anchor Cable and C-Shaped Tube can reduce the stress concentration of the interaction between the joint surface and the surrounding rock and reduce the damage to the surrounding rock.