The invention relates to a lightning arrester testing tool in the field of high-voltage electric appliances, the lightning arrester testing tool includes an insulation cylinder, a transition cylinder, and a tool insulator arranged between the insulation cylinder and the transition cylinder, a first conductive rod is arranged in the insulation cylinder, the tool insulator and the insulation cylinder form a first air chamber, the tool insulator and the transition cylinder form a second air chamber, the first air chamber and the second air chamber are isolated from each other through the tool insulator, a first conductive body is embedded on the tool insulator, the side, facing the insulation cylinder, of the first conductive body is connected with the first conductive rod, and the other side of the first conductive body is provided with an electrical connection structure connected with a lightning arrester to be tested when in use. Compared with a lightning arrester tool in the prior art, the lightning arrester testing tool has the two air chambers that can be simultaneously inflated and deflated, thereby improving the work efficiency; and moreover, when one of the air chambers leaks, the other one cannot be influenced by the leakage, so that the safety performance of the lightning arrester testing tool is improved.