The invention relates to a low-capacity sample dielectric loss testing tool and a using method thereof. The low-capacity sample dielectric loss testing tool comprises overhead wiring pincers and is characterized in that the end portion of the overhead wiring pincers is in a flat shape, is hinged by a bolt to a horizontal support bar, and is locked tightly by a nut; the central line of the bolt is vertical to a horizontal plane; the back of the body of the overhead wiring pincers is provided with a hook for being connected to a high-voltage lead; the end portion of the hook is provided with external threads, is screwed into the body of the overhead wiring pincers, and is locked tightly; the other end of the horizontal support bar is supported on a horizontal table top; a support seat is disposed on the center of the horizontal table top; the end portion of the horizontal support bar passes through a through hole on the support seat and then is locked tightly by a nut; one end, far away from the overhead wiring pincers, of the horizontal table top is provided with a slideway vertical to the length direction of the horizontal support bar; a slide block is disposed in the slideway; and a wire support roller is supported on the top of the slide block. The low-capacity sample dielectric loss testing tool is easy to operate, reliable to use, and accurate in testing, and solves a problem fundamentally that a conventional testing tool is low in efficiency and influences testing accuracy in a testing process.