The utility model relates to a realize that high -tension bushing is situated between relatively and decrease and capacitance online test's auxiliary device, including insulating block, the ground connection downlead, the copper block replacement of shielding high -tension bushing's end spring earthing device is measure -alike insulating the block, a coaxial arrangement electrically conductive spring in the block, preforming in conductive spring's inner welding, preforming outside the welding of conductive spring's outer end, an outer end face bonding electrically conductive terminal of preforming outside, central system at insulating block has a through -hole, the terminal is worn out from the block through -hole, a ground connection downlead termination is on this terminal, other end directly grounded, install piezo -resistor on the ground connection downlead, with the parallelly connected switch no. 1 of installing respectively of piezo -resistor, switch no. 2. The utility model discloses use manpower sparingly, material resources, in time discover electrical equipment's latent failure, effectively reduce the number of times of electrical equipment emergence accident, the convenient defect of differentiating high -tension bushing effective more.