The invention relates to the field of measurement equipment, and discloses a connecting device of a lightning arrester commissioning test. The connecting device of a lightning arrester commissioning test includes a suspension unit, an insulation unit, a fixing unit and a connecting unit, wherein the suspension unit includes a U-shaped pedestal I and a connecting frame; the middle of the connectingframe is a connecting hole; the fixing unit includes a U-shaped pedestal II and a ball fixing base; a spherical groove is formed in the ball fixing base, and an opening is formed in the spherical groove; two ends of the insulation unit are respectively embedded with the U-shaped pedestal I and the U-shaped pedestal II and are connected through a bolt; the connecting unit includes a connecting ball, a connecting rod and a connecting hook; the connecting ball is fixed at one end of the connecting rod, and the other end of the connecting rod is fixedly connected to the connecting hook; the connecting ball is arranged in the spherical groove; and the diameter of the opening of the spherical groove is less than the diameter of the connecting ball. The connecting device of a lightning arrestercommissioning test achieves the aim of isolating high voltage from the ground, can effectively avoid current leakage, can improve the accuracy of test results and the testing efficiency, and is convenient for development of the lightning arrester commissioning test.